A very large negative magnetoresistance (LNMR) is observed in the insulating regime of the antiferromagnet BaMn2Bi2 when a magnetic field is applied perpendicular to the direction of the sublattice magnetization. High perpendicular magnetic field eventually suppresses the insulating behavior and allows BaMn2Bi2 to re-enter a metallic state. This effect is seemingly unrelated to any field induced magnetic phase transition, as measurements of magnetic susceptibility and specific heat did not find any anomaly as a function of magnetic fields at temperatures above 2K. The LNMR appears in both current-in-plane and current-out-of-plane settings, and Hall effects suggest that its origin lies in an extreme sensitivity of conduction processes of holelike carriers to the infinitesimal field-induced canting of the sublattice magnetization. The LNMR-induced metallic state may thus be associated with the breaking of the antiferromagnetic parity-time symmetry by perpendicular magnetic fields and/or the intricate multi-orbital electronic structure of BaMn2Bi2.
@article{arxiv.2010.00807,
title = {Large negative magnetoresistance in BaMn$_2$Bi$_2$ antiferromagnet},
author = {Takuma Ogasawara and Kim-Khuong Huynh and Time Tahara and Takanori Kida and Masayuki Hagiwara and Denis Arčon and Motoi Kimata and Stephane Yu Matsushita and Kazumasa Nagata and Katsumi Tanigaki},
journal= {arXiv preprint arXiv:2010.00807},
year = {2021}
}