Magnetoresistance and Anisotropic Spin Dynamics in Antiferromagnetic Semiconductor Eu$_5$Sn$_2$As$_6$

TL;DR

This study investigates Eu$_5$Sn$_2$As$_6$, revealing complex magnetic phases, colossal magnetoresistance, and anisotropic spin dynamics in a rare-earth antiferromagnetic semiconductor, with implications for spintronic applications.

Contribution

It provides the first detailed analysis of the magnetic and transport properties of Eu$_5$Sn$_2$As$_6$, highlighting its complex magnetic phases and colossal magnetoresistance phenomena.

Findings

Eu$_5$Sn$_2$As$_6$ orders as a canted antiferromagnet at 10.3 K.

Displays negative colossal magnetoresistance up to 6000-fold.

Exhibits complex magnetic phase cascade due to frustration.

Abstract

We report on the thermodynamic and transport properties of the rare-earth Zintl compound Eu$_5$Sn$_2$As$_6$, which orders as a canted antiferromagnetic magnetic semiconductor at 10.3~K. The system also displays a complex cascade of magnetic phases arising from geometric and magnetic exchange frustration, with high sensitivity to the application and direction of small magnetic fields. At low temperature, Eu$_5$Sn$_2$As$_6$ exhibits negative colossal magnetoresistance of up to a factor of $6\times10^3$. This may be a lower bound as the conductivity appears to be shunted by an unknown conduction channel, causing the resistivity to saturate. Mechanisms for the low temperature saturation of resistivity are discussed.