Anomalous magnetotransport in (Y$_{1-x}$Gd$_{x}$)Co$_{2}$ alloys: interplay of disorder and itinerant metamagnetism

TL;DR

This paper introduces a new mechanism for magnetoresistivity in disordered itinerant metamagnets, demonstrated through (Y$_{1-x}$Gd$_{x}$)Co$_{2}$ alloys, linking structural disorder and metamagnetic instability to unusual magnetoresistive behavior.

Contribution

It presents a novel explanation for magnetoresistivity involving the interplay of disorder and itinerant metamagnetism in alloys, supported by experimental data.

Findings

Large positive magnetoresistivity observed in alloys with magnetic ground state.

Unusual magnetoresistivity linked to structural disorder and metamagnetic instability.

Mechanism applicable to a broad class of materials with magnetic disorder.

Abstract

New mechanism of magnetoresistivity in itinerant metamagnets with a structural disorder is introduced basing on analysis of experimental results on magnetoresistivity, susceptibility, and magnetization of structurally disordered alloys (Y$_{1-x}$Gd$_{x}$)Co$_{2}$. In this series, YCo$_{2}$ is an enhanced Pauli paramagnet, whereas GdCo$_{2}$ is a ferrimagnet (T$_{\rm c}$=400 K) with Gd sublattice coupled antiferromagnetically to the itinerant Co-3d electrons. The alloys are paramagnetic for $x < 0.12$. Large positive magnetoresistivity has been observed in the alloys with magnetic ground state at temperatures T$<$T$_{\rm c}$. We show that this unusual feature is linked to a combination of structural disorder and metamagnetic instability of itinerant Co-3d electrons. This new mechanism of the magnetoresistivity is common for a broad class of materials featuring a static magnetic disorder and itinerant metamagnetism.