# Mechanical dissipation at a tip-induced Kondo onset

## TL;DR

This paper models the mechanical dissipation associated with the Kondo effect's onset or demise in magnetic impurities, revealing temperature-dependent dissipation peaks that could be detected via atomic force microscopy.

## Contribution

It introduces a theoretical framework for understanding mechanical dissipation at a Kondo transition, combining simple resonant level models and advanced Anderson impurity models with numerical renormalization group techniques.

## Key findings

- Dissipation peaks are proportional to hybridization and temperature-dependent factors.
- Many-body effects modify dissipation, showing a peak proportional to $T_K | ext{log} T|$ near $T o T_K$.
- Potential for detecting Kondo dissipation in atomic force microscopy is discussed.

## Abstract

The onset or demise of Kondo effect in a magnetic impurity on a metal surface can be triggered, as often observed, by the simple mechanical nudging of a tip. This mechanically-driven quantum phase transition must reflect in a corresponding mechanical dissipation peak; yet, this kind of effect has not been focused upon so far. Aiming at the simplest theoretical modeling, we initially treat the impurity as a non-interacting resonant level turned cyclically on and off, and obtain a dissipation per cycle which is proportional to the hybridization $\Gamma$, with a characteristic temperature dependent resonant peak value. A better treatment is obtained next by solving an Anderson impurity model by numerical renormalization group. Here, many body effects yield a dissipation whose peak value is now proportional to $T_K |\log T|$ so long as $T\sim T_K$, followed for $T\sim \Gamma$ by a second high temperature regime where dissipation is proportional to $\Gamma|\log T|$. The detectability of Kondo mechanical dissipation in atomic force microscopy is discussed.