Out of equilibrium transport through an Anderson impurity: Probing scaling laws within the equation of motion approach

C. A. BALSEIRO, G. USAJ AND M. J. SÁNCHEZ

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Año: 2010 vol. 22 p. 425602 - 4256029

0953-8984

p { margin-bottom: 0.08in; } We study non-equilibrium electron transport through a quantum impurity coupled to metallic leads using the equation of motion technique at finite temperature T . Assuming that theinteractions are taking place solely in the impurity and focusing on the infinite Hubbard limit, we compute the out of equilibrium density of states and the differential conductance G 2 (T, V ) in order to test several scaling laws. We find that G 2 (T, V )/G 2 (T, 0) is a universal function of both eV /TK and T /TK , TK being the Kondo temperature. The effect of an in-plane magnetic field on the splitting of the zero bias anomaly in the differential conductance is also analyzed.For a Zeeman splitting , the computed differential conductance peak splitting depends only on Delta/ TK , and for large fields approaches the value of 2 . Besides studying the traditional twoleads setup, we also consider other configurations that mimic recent experiments, namely, an impurity embedded in a mesoscopic wire and the presence of a third weakly coupled lead. In these cases, a double peak structure of the Kondo resonance is clearly obtained in the differential conductance while the amplitude of the highest peak is shown to decrease as ln(eV /TK ). Several features of these results are in qualitative agreement with recent experimental observations reported on quantum dots.