Temperature dependence of electronic transport through molecular magnets in the Kondo regime

TL;DR

This paper investigates how temperature affects electronic transport in molecular magnets and similar nanostructures within the Kondo regime, revealing complex behaviors like a two-stage Kondo effect and quantum phase transitions.

Contribution

It provides a detailed analysis of temperature-dependent conductance in systems with magnetic anisotropy, uncovering new phenomena such as additional conductance peaks and the influence of exchange coupling sign.

Findings

Identification of a two-stage Kondo effect as temperature varies

Discovery of additional conductance peaks at specific temperatures

Dependence of conductance behavior on the sign of exchange coupling J

Abstract

The effects of finite temperature in transport through nanoscopic systems exhibiting uniaxial magnetic anisotropy D, such as molecular magnets, adatoms, or quantum dots side-coupled to a large spin are analyzed in the Kondo regime. The linear-response conductance is calculated by means of the full density-matrix numerical renormalization group method as a function of temperature T, magnetic anisotropy D, and exchange coupling J between the molecule's core spin and the orbital level. It is shown that such system displays a two-stage Kondo effect as a function of temperature and a quantum phase transition as a function of the exchange coupling J. Moreover, additional peaks are found in the linear conductance for temperatures of the order of T\sim|J| and T\simD. It is also shown that the conductance variation with T remarkably depends on the sign of the exchange coupling J.