To probe quantum criticality with scanning tunneling spectroscopy

TL;DR

This paper explores how quantum criticality influences tunneling conductance, revealing suppression of Fano resonance and unique conductance features in multichannel Kondo systems using advanced theoretical methods.

Contribution

It demonstrates that quantum criticality causes a weak Fano line-shape with a sharp zero-energy cusp and predicts no peak shift in multichannel Kondo conductance, contrasting with Fermi liquid behavior.

Findings

Quantum criticality suppresses Fano resonance in tunneling conductance.

Multichannel Kondo effect shows a weak Fano line-shape with a zero-energy cusp.

No shift of the Fano peak occurs in multichannel Kondo, unlike in single-channel cases.

Abstract

We investigate the role of quantum coherence in tunneling conductance, where quantum criticality turns out to suppress Fano resonance. Based on the nonequilibrium noncrossing approximation, we show that the linear tunneling conductance exhibits weak Fano line-shape with sharp cusp at zero energy in the multichannel Kondo effect, resulting from incoherence associated with quantum criticality of impurity dynamics. In particular, shift of the peak position in the Fano resonance is predicted not to occur for the multichannel Kondo effect, distinguished from the Fermi liquid theory in the single channel Kondo effect.