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Perera et al, unpublished.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