Composition induced metal-insulator quantum phase transition in the Heusler type Fe2VAl

TL;DR

This study investigates the quantum phase transition between metal and insulator in the Heusler compound Fe2VAl, revealing critical behavior and magnetic state changes induced by composition, pressure, and magnetic field.

Contribution

It demonstrates a composition-induced metal-insulator quantum phase transition in Fe2VAl and characterizes the associated magnetic and electronic critical phenomena.

Findings

Quantum phase transition at x = -0.05 with finite zero-temperature conductivity

Emergence of localized paramagnetism below x = -0.05

Itinerant ferromagnetism above x = 0.05 with Griffiths phase features

Abstract

We report the magnetism and transport properties of the Heusler compound Fe2+xV1-xAl at -0.10 < x < 0.10 under pressure and a magnetic field. A metal-insulator quantum phase transition occurred at x = -0.05. Application of pressure or a magnetic field facilitated the emergence of finite zero-temperature conductivity around the critical point, which scaled approximately according to the power law. At x < -0.05, a localized paramagnetic spin appeared, whereas above the ferromagnetic quantum critical point at x = 0.05, itinerant ferromagnetism was established. At the quantum critical points at x = -0.05 and 0.05, the resistivity and specific heat exhibited singularities characteristic of a Griffiths phase appearing as an inhomogeneous electronic state.