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Kondo Physics and Many-Body Effects in Quantum Dots and Molecular Junctions

Ruiz-Tijerina, David A.
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385982088

Abstract Details

2013, Doctor of Philosophy (PhD), Ohio University, Physics and Astronomy (Arts and Sciences).
In this document we present a study of the thermodynamic and transport properties of two kinds of quantum impurity systems in the Kondo regime. The first system consists of a spin-1 molecule in which mechanical stretching along the transport axis produces a magnetic anisotropy. We find that a generic coupling between a vibrational mode along this axis and the molecular spin induces a correction to the magnetic anisotropy, driving the ground state of the system into a non-Fermi-liquid phase. A transition into a Fermi-liquid ground state can then be induced by means of stretching, going through an underscreened spin-1 Kondo ground state at zero effective anisotropy. In the second system we study the effects of a charge detector, implemented by a quantum point-contact (QPC), on the Kondo state of a nearby spin-1/2 quantum dot (QD). While making the charge detection possible, the Coulomb interaction between the electrons traversing the QPC and those within the QD contribute to decoherence of the Kondo state. By modeling the QPC as two metallic terminals connected to an intermediate localized level, we can explore three transport regimes of the detector: a zero-conductance regime, a finite-conductance regime in mixed valence, and unitary conductance in a Kondo ground state that has been suggested as an explanation to the "0.7 anomaly" in QPCs. Transitions between these different ground states can be achieved by tuning the strength of a capacitive coupling that parameterizes the electrostatic interaction.
Sergio Ulloa, Prof. (Advisor)
Wojciech Jadwisienczak, Ph.D (Committee Member)
Saw Hla, Prof. (Committee Member)
Horacio Castillo, Ph.D. (Committee Member)
Nancy Sandler, Ph.D. (Committee Member)
134 p.
Condensed Matter Physics; Low Temperature Physics; Nanoscience; Nanotechnology; Physics; Quantum Physics; Solid State Physics
NRG; Numerical Renormalization Group; Kondo effect; many body physics; quantum phase transition; molecular junction; quantum dot; quantum point contact; electronic transport; highly correlated electrons; capacitive coupling; charge detector

Recommended Citations

Citations

  • Ruiz-Tijerina, D. A. (2013). Kondo Physics and Many-Body Effects in Quantum Dots and Molecular Junctions [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385982088

    APA Style (7th edition)

  • Ruiz-Tijerina, David. Kondo Physics and Many-Body Effects in Quantum Dots and Molecular Junctions. 2013. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385982088.

    MLA Style (8th edition)

  • Ruiz-Tijerina, David. "Kondo Physics and Many-Body Effects in Quantum Dots and Molecular Junctions." Doctoral dissertation, Ohio University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385982088

    Chicago Manual of Style (17th edition)

ohiou1385982088
1,516
© 2013, some rights reserved.Creative Commons License Kondo Physics and Many-Body Effects in Quantum Dots and Molecular Junctions by David A. Ruiz-Tijerina is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Ohio University and OhioLINK.