YbRh2Si2: Quantum tricritical behavior in itinerant electron systems

TL;DR

This paper introduces a quantum tricritical point (QTCP) framework to explain non-Fermi-liquid behaviors in YbRh2Si2, linking quantum phase transition characteristics with unconventional thermodynamic properties.

Contribution

It presents a novel spin fluctuation theory for the QTCP that accounts for the non-Fermi-liquid phenomena observed in YbRh2Si2.

Findings

Diverging ferromagnetic susceptibility at the antiferromagnetic transition

Unconventional power-law dependence in thermodynamic quantities

Quantum tricritical point explains non-Fermi-liquid behavior

Abstract

We propose that proximity of the first-order transition manifested by the quantum tricritical point (QTCP) explains non-Fermi-liquid properties of YbRh2Si2. Here, at the QTCP, a continuous phase transition changes into first order at zero temperature. The non-Fermi-liquid behaviors of YbRh2Si2 are puzzling in two aspects; diverging ferromagnetic susceptibility at the antiferromagnetic transition and unconventional power-law dependence in thermodynamic quantities. These puzzles are solved by an unconventional criticality derived from our spin fluctuation theory for the QTCP.