Signatures of phase transitions in the microwave response of YbRh2Si2

TL;DR

This study employs microwave spectroscopy with superconducting resonators to investigate charge dynamics and detect phase transitions in YbRh2Si2 near its quantum critical point, revealing insights into its electronic phase behavior.

Contribution

It introduces a microwave spectroscopic method to probe quantum criticality and phase transitions in heavy-fermion materials like YbRh2Si2.

Findings

Detected signatures of phase transitions in YbRh2Si2

Observed deviations from Fermi-liquid behavior near quantum critical point

Provided dynamic response data across different electronic regimes

Abstract

We used a spectroscopic microwave technique utilizing superconducting stripline resonators at frequencies between 3 GHz and 15 GHz to examine the charge dynamics of YbRh2Si2 at temperatures and magnetic fields close to the quantum critical point. The different electronic phases of this heavy-fermion compound, in particular the antiferromagnetic, Fermi-liquid, and non-Fermi-liquid regimes, were probed with temperature-dependent microwave measurements between 40 mK and 600 mK at a set of different magnetic fields up to 140 mT. Signatures of phase transitions were observed, which give information about the dynamic response of this peculiar material that exhibits field-tuned quantum criticality and pronounced deviations from Fermi-liquid theory.