Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields
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2008
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu12221867842021-08-03T05:54:35Z Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields Gopalakrishnan, Gokul Physics 2DEG electron drag phonon drag intermediate magnetic fields Landau level broadening bilayer magnetotransport <p>The discovery of the integer and fractional quantum Hall effects have broadened the exploration of the two-dimensional electron gas to regimes where complex and exciting physics lay previously hidden. While many experimental investigations have focused on the regime of large magnetic fields where transport properties are determined by contributions from a single Landau level, the regime of intermediate fields, where multiple Landau levels are involved, has been much less explored. This dissertation is a report on a previously unobserved interaction probed by a novel type of magneto-transport measurement performed in this intermediate regime, in bilayer two-dimensional electron systems. </p><p>This measurement technique, known as electron drag, directly measures interlayer electron-electron scattering rates, by measuring the voltage induced in one of the layers when a current is driven through the other. The scattering mechanism, which may be Coulomb or phonon mediated, depends critically on both the separation between the layers and the electron density. When electron drag is measured in the presence of a perpendicular magnetic field in suitable samples, the resulting magnetodrag signal reveals new information about the electronic states as well as properties of a phonon mediated scattering mechanism.</p><p>This phonon scattering mechanism is reflected in previously unobserved oscillations. These oscillations, which are periodic in the inverse field, are argued to arise from a resonant interlayer exchange of 2k<sub>F</sub> phonons. Measurements of the temperature, density and layer-spacing dependences of magnetodrag resistivity are reported and are shown to confirm this particular mechanism. Additionally, analysis of the temperature dependence reveals a strong sensitivity to Landau level widths. Based on this analysis, a means of characterizing the broadening of Landau levels and hence, electronic lifetimes in this regime, which are otherwise difficult to characterize, is proposed.</p> 2008-10-07 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1222186784 http://rave.ohiolink.edu/etdc/view?acc_num=osu1222186784 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 |
| sources |
NDLTD |
| topic |
Physics 2DEG electron drag phonon drag intermediate magnetic fields Landau level broadening bilayer magnetotransport |
| spellingShingle |
Physics 2DEG electron drag phonon drag intermediate magnetic fields Landau level broadening bilayer magnetotransport Gopalakrishnan, Gokul Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields |
| author |
Gopalakrishnan, Gokul |
| author_facet |
Gopalakrishnan, Gokul |
| author_sort |
Gopalakrishnan, Gokul |
| title |
Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields |
| title_short |
Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields |
| title_full |
Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields |
| title_fullStr |
Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields |
| title_full_unstemmed |
Phonon Exchange by Two-Dimensional Electrons in Intermediate Magnetic Fields |
| title_sort |
phonon exchange by two-dimensional electrons in intermediate magnetic fields |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2008 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1222186784 |
| work_keys_str_mv |
AT gopalakrishnangokul phononexchangebytwodimensionalelectronsinintermediatemagneticfields |
| _version_ |
1719427588541120512 |