Condensed Matter Seminar Series

Exploring the Kondo Effect in Quantum Dots and Magnetic Molecules

Sergio Ulloa

Ohio University, Dept. of Physics and Nanoscale and Quantum Phenomena Inst.

Thursday, February 25,  11:00 am,  Room 298,  Physics Building

    The screening of a local magnetic moment by itinerant electrons in metals creates a highly correlated Kondo state, where the electronic spin plays a leading role. Recent experimental advances in drastically different areas have fueled a renaissance in the study of this fascinating phenomenon: Coulomb blockaded quantum dots in semiconductors as well as magnetic adatoms and molecules on metallic surfaces have given rise to new challenges and resulted in our revisiting known questions about spin correlations in this state.
    In this talk I will describe some of the open questions and interesting Kondo behavior made evident in beautiful STM experiments on surfaces with adsorbed magnetic molecules [1]. I
will also describe theoretical predictions of finite-temperature experimental signatures of a quantum phase transition (QPT) occurring as a suitably tuned double quantum dot system is brought into and through appropriate system conditions. These regimes can be reached
in-situ by applied voltages that determine dot sizes and barriers, dot occupations, and the specific position of individual dot orbitals. This unique tunability, as well as possible magnetic fields/fluxes allow one to explore the physics of QPTs in a single system, without the typical need to study different samples [2].

[1] U.G.E. Perera et al, unpublished.
[2] L. Dias da Silva et al, PRL 102, 166806 (2009); E. Vernek et al, PRB 80, 041302(R) (2009).

Host: Harold Baranger

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