Gough, Jonathan;
(2024)
Localization & Weak Electron-Phonon Coupling.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Over the last few years, Localization has seen a resurgence in popularity. This is partly due to the development of many body localization and the various research challenges associated with it. The holy grail of this new wave of localization research is the experimental verification of a perfect insulator. We contribute to this goal by experimentally identifying a signature of electron-phonon decoupling, a prerequisite for a perfect insulator. Within the context of many body localization, this has previously only been observed in superconducting materials in the presence of an external magnetic field. We observe this effect in ion-damaged InSb thin films. Using an ion-damage procedure we can directly compare insulating and metallic behaviour in a single sample. On the metallic side we observe and analyse a variety of phase coherence effects. We suggest the saturation in the phase coherence length on the metallic side and the discontinuous IV characteristics on the insulating side are both consequences of weak electron-phonon coupling. This is supported by calculations of the electron-phonon coupling strength. Our results suggest that carriers in strongly localized systems may be more mobile than originally thought. We present a simple phenomenological model that attempts to describe how strongly localized carriers can be deflected by a Lorentz force to establish a Hall voltage and be heated by an electric field. Our results are also compared to various existing models and critically analysed. These models relate to metallic islands, correlated systems and diverging localization lengths. We find that no single model can explain the Joule heating within our samples, thermally activated mobility and interaction effects near the metal insulator transition. From our analysis we identify future avenues of research.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Localization & Weak Electron-Phonon Coupling |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | opyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10192645 |
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