Hall effects in giant magnetoresistance system BaMn₂Bi₂

A new kind of giant magnetoresistance (GMR) is observed in the family of G-type antiferromagnets BaMn₂Pn₂ ’s, where Pn denotes pnictide elements of As, Sb, and Bi. The -98% GMR appears intriguingly with an unique angular dependence under rotating magnetic fields [1, 2] on the background of a complex magnetic hexadecapole ordering that preserves the parity-time symmetry even though the parity and time reversal symmetries are broken respectively[3]. Among the BaMn₂Pn₂ ’s , BaMn₂Bi₂ shows the largest MR in the smallest magnetic field range and therefore is the key material of the BaMn₂Pn₂ family [1] for further detailed studies. We have measured the angular dependence of magnetoresistance and Hall effect of BaMn₂Bi₂ to investigate the effect of magnetic field on the electrical conductivity. The results of our analyses suggest that the observed GMR stems from a large enhancement in the mobility of hole-like carriers induced by magnetic fields.
[1] K. K. Huynh et al. submitted (2018)
[2] T. Ogasawara et al. submitted (2018)
[3] H. Watanabe et al. Phys. Rev. B 96, 064432 (2017)