Metallic State in Cubic FeGe beyond its Quantum Phase Transition

TL;DR

This study investigates the high-pressure behavior of cubic FeGe, revealing a metallic state beyond its quantum phase transition with deviations from Fermi-liquid behavior and possible structural transitions.

Contribution

It provides new insights into the suppression of magnetic order and the nature of the metallic state in cubic FeGe under high pressure, including structural disorder effects.

Findings

Suppression of helical magnetic order at ~19 GPa

Deviations from Fermi-liquid behavior above critical pressure

Evidence of a possible first-order structural transition

Abstract

We report on results of electrical resistivity and structural investigations on the cubic modification of FeGe under high pressure. The long-wavelength helical order ($T_C=280$ K) is suppressed at a critical pressure $p_c\approx 19$ GPa. An anomaly in the resistivity data at $T_X(p)$ and strong deviations from a Fermi-liquid behavior in a wide pressure range above $p_c$ suggest that the suppression of $T_C$ disagrees with the standard notion of a quantum critical phase transition. The metallic ground state persisting at high pressure can be described by band-structure calculations if structural disorder due to zero-point motion is included. Discontinuous changes in the pressure dependence of the shortest Fe-Ge interatomic distance occurring close to the $T_C(p)$ phase line could be interpreted as a symmetry-conserving transition of first order.