Large negative magnetoresistance in the new antiferromagnetic rare-earth dichalcogenide EuTe$_2$

TL;DR

This study introduces EuTe$_2$, a new antiferromagnetic rare-earth dichalcogenide exhibiting giant negative magnetoresistance near 100%, with magnetic transitions tunable by magnetic fields and underlying electronic correlations.

Contribution

It reports the synthesis, magnetic properties, and electronic structure of EuTe$_2$, revealing the interplay of RKKY and Kondo interactions responsible for its large negative magnetoresistance.

Findings

Antiferromagnetic transition at 11 K.

Giant negative magnetoresistance near 100%.

Magnetic transitions tunable by magnetic field.

Abstract

We report the synthesis and characterization of a rare-earth dichalcogenide EuTe$_2$. An antiferromagnetic transition was found at T$_M$ = 11 K. The antiferromagnetic order can be tuned by an applied magnetic field to access a first-order spin flop transition and a spin flip transition. These transitions are associated with a giant negative magnetoresistance with a value of nearly 100\%. Heat capacity measurements reveal strong electronic correlations and a reduced magnetic entropy. Furthermore, density functional theory calculations demonstrate that the electrons near the Fermi surface mainly originate from the Te 5$p$ orbitals and the magnetism is dominated by localized electrons from the Eu 4$f$ orbitals. These results suggest that both the RKKY and Kondo interactions between the local moments and itinerant electrons play crucial roles in the magnetism and large negative magnetoresistance of EuTe$_2$.