Kondo nanomechanical dissipation in the driven Anderson impurity model

TL;DR

This paper investigates how nanomechanical dissipation during Kondo to non-Kondo state switching depends on the switching speed, revealing that significant dissipation occurs only with rapid switching within the Kondo time scale, using advanced computational methods.

Contribution

It introduces a time-dependent variational algorithm to analyze dissipation in the driven Anderson impurity model, highlighting the importance of switching speed relative to the Kondo time scale.

Findings

Dissipation drops from maximum to zero as switching slows down.

Fast switching within the Kondo time scale induces significant dissipation.

Current experimental setups may struggle to achieve the required switching speed.

Abstract

The cyclic sudden switching of a magnetic impurity from Kondo to a non-Kondo state and back was recently shown to involve an important dissipation of the order of several $k_BT_K$ per cycle. The possibility to reveal this and other electronic processes through nanomechanical dissipation by e.g., ultrasensitive Atomic Force Microscope (AFM) tools currently represents an unusual and interesting form of spectroscopy. Here we explore the dependence on the switching time of the expected dissipation, a quantity whose magnitude is physically expected to drop from maximum to zero between sudden and slow switching, respectively. By applying a recently established matrix-product-state based time-dependent variational algorithm to the magnetic field-induced Kondo switching in an Anderson model of the magnetic impurity, we find that dissipation requires switching within the Kondo time scale $\hbar(k_B T_K)^{-1}$ or faster. While such a fast switching seems problematic for current AFM setups, the challenge is open for future means to detect this dissipation by time-dependent magnetic fields, electrostatic impurity level shift, or hybridization switching.