Unusual Magnetic Properties in Layered Magnetic Topological Insulator EuSn2As2

TL;DR

This study investigates the magnetic and transport properties of EuSn2As2, revealing complex magnetic phase transitions from antiferromagnetic to ferromagnetic states under applied magnetic fields.

Contribution

It provides the first systematic magnetoresistance and magnetization measurements on EuSn2As2, uncovering detailed magnetic phase transitions and their relation to topological properties.

Findings

EuSn2As2 undergoes an AFM transition at 21 K.

Magnetization shows two plateaus at low temperature.

Complex magnetic transitions from AFM to canted and polarized FM states.

Abstract

EuSn2As2 with layered rhombohedral crystal structure is proposed to be a candidate of intrinsic antiferromagnetic (AFM) topological insulator. Here, we have investigated systematic magnetoresistance (MR) and magnetization measurements on the high quality EuSn2As2 single crystal with the magnetic field both parallel and perpendicular to (00l) plane. Both the kink of magnetic susceptibility and longitudinal resistivity reveal that EuSn2An2 undergoes an AFM transition at TN = 21 K. At T = 2 K, the magnetization exhibits two successive plateaus of ~ 5.6 {\mu}B/Eu and ~ 6.6 {\mu}B/Eu at the corresponding critical magnetic fields. Combined with the negative longitudinal MR and abnormal Hall resistance, we demonstrate that EuSn2An2 undergoes complicated magnetic transitions from an AFM state to a canted ferromagnetic (FM) state at Hc and then to a polarized FM state at Hs as the magnetic field increase.