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Electron-Electron Interactions in Complex-Oxide Nanodevices

Tomczyk, Michelle (2017) Electron-Electron Interactions in Complex-Oxide Nanodevices. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Strontium titanate (SrTiO3) is a superconducting semiconductor possessing characteristics which suggest an unconventional pairing mechanism; however, direct experimental insight into the nature of electron pairing in SrTiO3 has remained elusive. SrTiO3-based interfaces can provide new clues about electronic interactions leading to pairing. In particular, the electronic system at the interface of LaAlO3 and SrTiO3 hosts a broad array of emergent phenomena, including superconductivity, spin-orbit coupling, and magnetism, providing a tantalizing platform to study electronic interactions.

In this dissertation, nanodevices with well-characterized quantum behavior are used as probes of the interfacial electronic system. These devices enable coherent single-electron and single-subband resolution of electronic states, which can elucidate the microscopic details of electronic interactions. Tunneling behavior through nanowire quantum dots reveals the existence of electron pairs far outside the superconducting regime. While this suggests strong attractive interactions, Andreev transport at higher gate voltages indicates a gate-tunable sign change of electron-electron interactions. Ballistic transport over micrometer distances produces quantum interference oscillations in nanowire cavities, and also leads to quantized conductance plateaus in electron waveguide devices. Evolution of the plateaus in an applied magnetic field reveals details of the strength and variation of the electron pairing, and other related physical properties. These results provide guidance to theoretical predictions of the microscopic origins of the electron pairing interactions.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Tomczyk, Michelletomczykmr@levylab.orgmrt440000-0003-4770-2117
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairLevy,
Committee MemberPekker,
Committee MemberD'Urso,
Committee MemberMueller,
Committee MemberWaldeck,
Date: 28 September 2017
Date Type: Publication
Defense Date: 12 July 2017
Approval Date: 28 September 2017
Submission Date: 8 August 2017
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 155
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Electron interactions complex-oxide nanodevice electron correlations c-AFM lithography
Date Deposited: 29 Sep 2017 00:56
Last Modified: 28 Sep 2018 05:15


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