A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors
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The Ohio State University / OhioLINK
2012
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1343745915 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu13437459152021-08-03T06:06:17Z A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors Jaworski, Christopher M. Condensed Matter Physics Mechanical Engineering thermoelectricity spin thermal effect semiconductors PbTe InSb <p>The dimensionless thermoelectric figure of merit, zT, is used to characterize the conversion efficiency of thermoelectric materials. In this dissertation, we include experimental results on new p-type semiconducting alloys based on lead telluride that have higher zT values than historical materials. Through alloying PbTe:Tl with sulfur, we demonstrate an increase in zT over the parent material PbTe:Tl. Next, we remove the toxic element Tl from the PbTe/PbS alloy and retain the high efficiency via doping heavy valence band in PbTe, a separate mechanism than the high-zT resonant level doping achieved by the impurity Tl. We present experimental evidence relevant to the valence band structure of PbTe alloys at elevated temperature and demonstrate that these alloys remain direct gap semiconductors at temperatures relevant to automotive thermoelectric waste heat recovery (<850K).</p><p>Secondly, we report the first confirmation measurement of a new effect – the spin-Seebeck effect – in thin films of GaMnAs, of work by researchers at Tohoku University two years prior on NiFe. The spin-Seebeck effect is a thermally driven spin distribution – the spin analog to the charge-Seebeck effect, and is measured using the inverse spin Hall effect in platinum transducers that are attached to the spin-polarized material. We report extensive measurements over temperature and at various positions along the sample. We show that this effect is phonon driven, and that a phonon-magnon drag is capable of enhancing the magnitude of this effect, much like phonon-electron drag in charge Seebeck. Lastly, by using a non-magnetic material with large spin orbit interaction, we show the magnitude of this effect can reach the order of mV/K, whereas in ferromagnets it is order µV/K. Here, external magnetic field generates the necessary spin splitting. The discovery of this effect may allow for solid state heat engines based off spin, as an analog to thermoelectricity heat engines.</p> 2012-08-27 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1343745915 http://rave.ohiolink.edu/etdc/view?acc_num=osu1343745915 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
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NDLTD |
| topic |
Condensed Matter Physics Mechanical Engineering thermoelectricity spin thermal effect semiconductors PbTe InSb |
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Condensed Matter Physics Mechanical Engineering thermoelectricity spin thermal effect semiconductors PbTe InSb Jaworski, Christopher M. A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors |
| author |
Jaworski, Christopher M. |
| author_facet |
Jaworski, Christopher M. |
| author_sort |
Jaworski, Christopher M. |
| title |
A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors |
| title_short |
A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors |
| title_full |
A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors |
| title_fullStr |
A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors |
| title_full_unstemmed |
A Thermoelectric Investigation of Selected Lead Salts and the Spin‐Seebeck Effect in Semiconductors |
| title_sort |
thermoelectric investigation of selected lead salts and the spin‐seebeck effect in semiconductors |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2012 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1343745915 |
| work_keys_str_mv |
AT jaworskichristopherm athermoelectricinvestigationofselectedleadsaltsandthespinseebeckeffectinsemiconductors AT jaworskichristopherm thermoelectricinvestigationofselectedleadsaltsandthespinseebeckeffectinsemiconductors |
| _version_ |
1719430934865903616 |