Non-adiabatic Transport in Single-Electron Transistors in the Kondo Regime – Andrei Kogan

Date: Mon. November 23rd, 2015, 12:30 pm-1:30 pm
Location: Rockefeller 221

Magnetic impurities in conductors alter the Fermi sea: A many-body state (A Kondo singlet) is formed that entangles itinerant carriers and the impurity site. This causes a sharp rearrangement of the density of states near the Fermi surface into a hierarchical set governed by a single energy parameter Tk, the Kondo temperature. Equilibrium physics of such electronic “knots” scales with Tk and is highly universal: impurities that differ microscopically from one another yet have similar Kondo temperatures produce Kondo states with similar properties. Recent studies of Kondo physics with voltage-controllable spin traps known as Single-Electron Transistors (SETs) have focused on nonequiibrium Kondo phenomena, sensitive to the interplay between coherent correlations and dissipative effects, aiming to understand the extent of Kondo universality away from equilibrium. In this talk, I will give a brief overview of experimental work on nonequillibrium Kondo physics and present our transport measurements in SETs with microwave-frequency modulation. We observe an onset of nonadiabatic effects in conductance at frequencies comparable to the Kondo temperature, which suggest that the Kondo temperature may define a universal scale for dynamic phenomena. We also compare the results to theoretical predictions for the universal spin decoherence rate in Kondo systems.