Field-induced non-Fermi-liquid resistivity of stoichiometric YbAgGe single crystals

TL;DR

This study explores the low-temperature resistivity of YbAgGe single crystals under magnetic fields, revealing unusual non-Fermi-liquid behavior and quantum criticality near magnetic phase suppression.

Contribution

It provides the first detailed phase diagram extension to 70 mK and identifies field-induced non-Fermi-liquid resistivity in stoichiometric YbAgGe.

Findings

Critical magnetic fields for phase suppression determined

Unusual temperature dependence of resistivity observed

Fermi-liquid behavior recovered at high fields

Abstract

We have investigated hexagonal YbAgGe down to 70 mK by measuring the magnetic-field and temperature dependence of the resistivity rho of single crystals in fields up to 14 T. Our results extend the H-T phase diagram to the lowest temperatures for H applied in the basal plane and along the c-axis. In particular, critical fields for the suppression of several magnetic phases are determined. The temperature dependence of rho(T) is unusual: whereas at low H, rho(T) reveals a temperature exponent n>=2, we find 1<=n<1.5 and strong enhancement of the temperature dependence of rho(T) close to and beyond the highest critical field for each field direction. For H applied in the basal plane, at high fields a conventional T^2 dependence of rho(T) is reached above 10 T accompanied by an approach to saturation of a strong drop in the residual resistivity. YbAgGe appears to be one of few Yb-based stoichiometric systems, where quantum-critical behaviour may be induced by a magnetic field.