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<h2 class="hd hd-2 unit-title">Magnetoresistive Readback</h2>
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Magnetoresistive Readback
</h3>
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<h1>Exercise 3.1A</h1>
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<br/>
<p>
Review the lectures on Magnetoresistance. Then complete the following statements by selecting the correct terms from the dropdown menu. </p>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div class="multi-inputs-group" role="group"><p style="display:inline">1) Magnetoresistance is currently used for the </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_1" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_1" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_1">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_1_dummy_default">Select an option</option>
<option value="readback"> readback</option>
<option value="writing"> writing</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_1"/>
</div><p style="display:inline">process in hard disks.</p>
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<p style="display:inline">2) Magnetoresistance means that the </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_2" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_2" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_2">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_2_dummy_default">Select an option</option>
<option value="coercivity"> coercivity</option>
<option value="magnetization"> magnetization</option>
<option value="resistivity"> resistivity</option>
<option value="saturation"> saturation</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_2" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_2"/>
</div><p style="display:inline">of a material is a function of the magnetic field. Though all materials exhibit magnetoresistance, the strongest effects are seen in </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_3" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_3" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_3">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_3_dummy_default">Select an option</option>
<option value="diamagnets"> diamagnets</option>
<option value="insulators"> insulators</option>
<option value="magnetic materials"> magnetic materials</option>
<option value="paramagnets"> paramagnets</option>
<option value="semicondutors"> semicondutors</option>
</select>
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<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_3" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_3"/>
</div><br/>
<br/>
<b>Anisotropic Magnetoresistance (AMR)</b>
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<p style="display:inline">3) AMR means that there is a substantial change in resistivity depending on the </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_4" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_4" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_4">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_4_dummy_default">Select an option</option>
<option value="angle between"> angle between</option>
<option value="difference in magnitude between"> difference in magnitude between</option>
<option value="magnitudes of"> magnitudes of</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_4" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_4"/>
</div><p style="display:inline">the current and the magnetization vector. </p>
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<p style="display:inline">4) Magnetoresistance arises from the difference in </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_5" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_5" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_5">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_5_dummy_default">Select an option</option>
<option value="angular momentum"> angular momentum</option>
<option value="magnetization"> magnetization</option>
<option value="rotation"> rotation</option>
<option value="scattering"> scattering</option>
<option value="spin"> spin</option>
</select>
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<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_5" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_5"/>
</div><p style="display:inline">of spin-polarized electrons as they pass through the material. </p>
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<p style="display:inline">5) To make an AMR sensor, we begin with a thin strip or film of a magnetic material such as permalloy that initially has a direction of magnetization </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_6" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_6" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_6">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_6_dummy_default">Select an option</option>
<option value="0"> 0</option>
<option value="45"> 45</option>
<option value="90"> 90</option>
<option value="180"> 180</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_6" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_6"/>
</div><p style="display:inline">degrees to the current.</p>
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<p style="display:inline">6) When a </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_7" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_7" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_7">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_7_dummy_default">Select an option</option>
<option value="horizontal"> horizontal</option>
<option value="parallel"> parallel</option>
<option value="perpendicular"> perpendicular</option>
<option value="vertical"> vertical</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_7" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_7"/>
</div><p style="display:inline">magnetic field is applied, the direction of magnetization is pushed either up or down, producing a corresponding change in resistivity.</p>
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<p style="display:inline">7) AMR can produce a change in resistivity of </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_8" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_8" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_8">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_8_dummy_default">Select an option</option>
<option value="a few"> a few</option>
<option value="10"> 10</option>
<option value="50"> 50</option>
<option value="90"> 90</option>
<option value="600"> 600</option>
</select>
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<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_8" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_8"/>
</div><p style="display:inline">percent.</p>
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<b>Giant Magnetoresistance (GMR)</b>
<br/>
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<p style="display:inline">8)GMR can produce changes in resistivity from </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_9" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_9" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_9">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_9_dummy_default">Select an option</option>
<option value="a few"> a few</option>
<option value="10"> 10</option>
<option value="50"> 50</option>
<option value="90"> 90</option>
<option value="600"> 600</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_9" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_9"/>
</div><p style="display:inline">percent to as much as </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_10" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_10" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_10">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_10_dummy_default">Select an option</option>
<option value="a few"> a few</option>
<option value="10"> 10</option>
<option value="50"> 50</option>
<option value="90"> 90</option>
<option value="600"> 600</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_10" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_10"/>
</div><p style="display:inline">percent.</p>
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<p style="display:inline">9) GMR is observed in multilayer structures where </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_11" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_11" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_11">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_11_dummy_default">Select an option</option>
<option value="angular momentum"> angular momentum</option>
<option value="magnetization"> magnetization</option>
<option value="rotation"> rotation</option>
<option value="scattering"> scattering</option>
<option value="spin"> spin</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_11" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_11"/>
</div><p style="display:inline">, and therefore resistivity, depends on the magnetization of two layers with respect to one another. </p>
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<p style="display:inline">10) GMR is used in the readback heads of hard drives. A stack called a spin valve is used, with the following layers: </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_12" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_12" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_12">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_12_dummy_default">Select an option</option>
<option value="Antiferromagnet-Ferromagnet-Nonmagnet-Ferromagnet"> Antiferromagnet-Ferromagnet-Nonmagnet-Ferromagnet</option>
<option value="Antiferromagnet-Nonmagnet-Antiferromagnet-Ferromagnet"> Antiferromagnet-Nonmagnet-Antiferromagnet-Ferromagnet</option>
<option value="Ferromagnet-Antiferromagnet-Nonmagnet-Ferromagnet"> Ferromagnet-Antiferromagnet-Nonmagnet-Ferromagnet</option>
<option value="Ferromagnet-Nonmagnet-Ferromagnet-Nonmagnet"> Ferromagnet-Nonmagnet-Ferromagnet-Nonmagnet</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_12" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_12"/>
</div><br/>
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<p style="display:inline">11) The </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_13" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_13" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_13">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_13_dummy_default">Select an option</option>
<option value="antiferromagnetic"> antiferromagnetic</option>
<option value="ferromagnetic"> ferromagnetic</option>
<option value="insulating"> insulating</option>
<option value="nonmagnetic"> nonmagnetic</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_13" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_13"/>
</div><p style="display:inline">layer pins the adjacent </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_14" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_14" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_14">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_14_dummy_default">Select an option</option>
<option value="antiferromagnetic"> antiferromagnetic</option>
<option value="ferromagnetic"> ferromagnetic</option>
<option value="insulating"> insulating</option>
<option value="nonmagnetic"> nonmagnetic</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_14" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_14"/>
</div><p style="display:inline">layer. The other </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_15" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_15" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_15">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_15_dummy_default">Select an option</option>
<option value="antiferromagnetic"> antiferromagnetic</option>
<option value="ferromagnetic"> ferromagnetic</option>
<option value="insulating"> insulating</option>
<option value="nonmagnetic"> nonmagnetic</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_15" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_15"/>
</div><p style="display:inline">layer can rotate its magnetization in response to the fringing fields from the bits on the disk. The resistance of the stack depends on the </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_16" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_16" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_16">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_16_dummy_default">Select an option</option>
<option value="angle between"> angle between</option>
<option value="difference in magnitude between"> difference in magnitude between</option>
<option value="magnitudes of"> magnitudes of</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_16" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_16"/>
</div><p style="display:inline">magnetization directions in the two </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_17" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_17" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_17">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_17_dummy_default">Select an option</option>
<option value="antiferromagnetic"> antiferromagnetic</option>
<option value="ferromagnetic"> ferromagnetic</option>
<option value="insulating"> insulating</option>
<option value="nonmagnetic"> nonmagnetic</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_17" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_17"/>
</div><p style="display:inline">layers. </p>
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<br/>
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<br/>
<b>Tunneling Magnetoresistance (TMR)</b>
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<p style="display:inline">12) In TMR, the metallic nonmagnetic layer is replaced by </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_18" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_18" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_18">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_18_dummy_default">Select an option</option>
<option value="an antiferromagnetic"> an antiferromagnetic</option>
<option value="a ferromagnetic"> a ferromagnetic</option>
<option value="an insulating"> an insulating</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_18" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_18"/>
</div><p style="display:inline">layer.</p>
<br/>
<br/>
<p style="display:inline">13) If the </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_19" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_19" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_19">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_19_dummy_default">Select an option</option>
<option value="antiferromagnetic"> antiferromagnetic</option>
<option value="ferromagnetic"> ferromagnetic</option>
<option value="insulating"> insulating</option>
<option value="nonmagnetic"> nonmagnetic</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_19" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_19"/>
</div><p style="display:inline">layer is thin enough, tunneling can take place through the barrier. </p>
<br/>
<br/>
<p style="display:inline">14) If the magnetizations of the two layers are parallel, tunneling is much </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_20" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_20" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_20">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_20_dummy_default">Select an option</option>
<option value="easier"> easier</option>
<option value="harder"> harder</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_20" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_20"/>
</div><p style="display:inline">than if the magnetizations are antiparallel. </p>
<br/>
<br/>
<p style="display:inline">15) Resistance changes of up to </p>
<div class="inputtype option-input inline">
<select name="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_21" id="input_dcda22c24fcd4dd6bf978a4b22d1a870_2_21" aria-describedby="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_21">
<option value="option_dcda22c24fcd4dd6bf978a4b22d1a870_2_21_dummy_default">Select an option</option>
<option value="a few"> a few</option>
<option value="10"> 10</option>
<option value="50"> 50</option>
<option value="90"> 90</option>
<option value="600"> 600</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_dcda22c24fcd4dd6bf978a4b22d1a870_2_21" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_dcda22c24fcd4dd6bf978a4b22d1a870_2_21"/>
</div><p style="display:inline">percent can be achieved with TMR. </p>
</div></div>
</div>
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<input type="hidden" name="problem_id" value="Magnetoresistive Readback" />
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<h2 class="hd hd-2 unit-title">Optical and Magnetooptical Media</h2>
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<h3 class="hd hd-3 problem-header" id="ab3de582c8f947afb2a73bda3f6aece2-problem-title" aria-describedby="block-v1:MITx+3.15.3x+2T2017+type@problem+block@ab3de582c8f947afb2a73bda3f6aece2-problem-progress" tabindex="-1">
Exercise 3.2
</h3>
<div class="problem-progress" id="block-v1:MITx+3.15.3x+2T2017+type@problem+block@ab3de582c8f947afb2a73bda3f6aece2-problem-progress"></div>
<div class="problem">
<div>
<h1>Exercise 3.2</h1>
<br/>
<br/>
<p>
Review the lectures on Optical and Magnetooptical Media. Then complete the following statements by selecting the correct terms from the dropdown menu. </p>
<b>Magnetooptical Media</b>
<br/>
<br/>
<div class="wrapper-problem-response" tabindex="-1" aria-label="Question 1" role="group"><div class="multi-inputs-group" role="group"><p style="display:inline">1) Magnetooptical properties such as the </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_1" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_1" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_1">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_1_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_1" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_1"/>
</div><p style="display:inline">and the Kerr effect are examples of a coupling between magnetic and optical properties.</p>
<br/>
<br/>
<p style="display:inline">2) The Faraday effect causes polarized light to be rotated as it is </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_2" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_2" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_2">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_2_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_2" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_2"/>
</div><p style="display:inline">through a magnetic material.</p>
<br/>
<br/>
<p style="display:inline">3) The Kerr effect causes light to be rotated as it is </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_3" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_3" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_3">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_3_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_3" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_3"/>
</div><p style="display:inline">from a magnetic material. </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_4" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_4" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_4">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_4_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_4" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_4"/>
</div><p style="display:inline">transition metal alloys exhibit a particularly strong Kerr effect. </p>
<br/>
<br/>
<p style="display:inline">4) To write to a magnetooptical disk, a laser spot heats up a small portion of the disk, and a global </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_5" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_5" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_5">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_5_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_5" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_5"/>
</div><p style="display:inline">reverses the magnetization of the heated area. </p>
<br/>
<br/>
<p style="display:inline">5) A weaker laser is used to read a magnetooptical disk, and the </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_6" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_6" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_6">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_6_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_6" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_6"/>
</div><p style="display:inline">of the light shows us which way the spot is magnetized. </p>
<br/>
<br/>
<b>All-Optical Data Storage</b>
<br/>
<br/>
<p style="display:inline">1) DVDs and CDs utilize </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_7" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_7" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_7">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_7_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_7" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_7"/>
</div><p style="display:inline">data storage.</p>
<br/>
<br/>
<p style="display:inline">2) Data is encoded as small pits which lower the </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_8" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_8" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_8">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_8_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_8" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_8"/>
</div><p style="display:inline">of the surface.</p>
<br/>
<br/>
<p style="display:inline">3) The pitted surface is coated with a reflective material such as</p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_9" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_9" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_9">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_9_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
<div class="indicator-container">
<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_9" data-tooltip="Not yet answered.">
<span class="sr">unanswered</span><span class="status-icon" aria-hidden="true"/>
</span>
</div>
<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_9"/>
</div><p style="display:inline">and with a protective</p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_10" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_10" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_10">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_10_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
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<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_10"/>
</div><p style="display:inline">substrate.</p>
<br/>
<br/>
<p style="display:inline">4) To read an optical disk, a </p>
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<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_11" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_11" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_11">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_11_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
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<span class="status unanswered" id="status_ab3de582c8f947afb2a73bda3f6aece2_2_11" data-tooltip="Not yet answered.">
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<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_11"/>
</div><p style="display:inline">is passed over the pitted surface of the disk. </p>
<br/>
<br/>
<p style="display:inline">5) The dimensions of the pits are designed such that as the laser beam passes from a pit to a mesa, </p>
<div class="inputtype option-input inline">
<select name="input_ab3de582c8f947afb2a73bda3f6aece2_2_12" id="input_ab3de582c8f947afb2a73bda3f6aece2_2_12" aria-describedby="status_ab3de582c8f947afb2a73bda3f6aece2_2_12">
<option value="option_ab3de582c8f947afb2a73bda3f6aece2_2_12_dummy_default">Select an option</option>
<option value="aluminum"> aluminum</option>
<option value="destructive interference"> destructive interference</option>
<option value="Faraday effect"> Faraday effect</option>
<option value="Kerr rotation"> Kerr rotation</option>
<option value="laser beam"> laser beam</option>
<option value="magnetic field"> magnetic field</option>
<option value="optical"> optical</option>
<option value="polycarbonate"> polycarbonate</option>
<option value="rare earth"> rare earth</option>
<option value="reflected"> reflected</option>
<option value="reflectivity"> reflectivity</option>
<option value="transmitted"> transmitted</option>
</select>
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<p class="answer" id="answer_ab3de582c8f947afb2a73bda3f6aece2_2_12"/>
</div><p style="display:inline">occurs and the amount of reflected light decreases. </p>
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