Strange electrical transport: Colossal magnetoresistance via avoiding fully polarized magnetization in ferrimagnetic insulator Mn3Si2Te6

TL;DR

This paper reports a unique colossal magnetoresistance in Mn3Si2Te6, occurring only when magnetic field is applied along the hard axis, defying existing models and revealing novel electrical transport phenomena.

Contribution

It uncovers a new type of colossal magnetoresistance in a ferrimagnetic insulator that occurs only along the magnetic hard axis, challenging current understanding.

Findings

Resistivity drops by 7 orders of magnitude under magnetic field

Colossal magnetoresistance occurs only along the magnetic hard axis

Anisotropy field is unexpectedly high at 13 Tesla

Abstract

Colossal magnetoresistance is of great fundamental and technological significance and exists mostly in the manganites and a few other materials. Here we report colossal magnetoresistance that is starkly different from that in all other materials. The stoichiometric Mn3Si2Te6 is an insulator featuring a ferrimagnetic transition at 78 K. The resistivity drops by 7 orders of magnitude with an applied magnetic field above 9 Tesla, leading to an insulator-metal transition at up to 130 K. However, the colossal magnetoresistance occurs only when the magnetic field is applied along the magnetic hard axis and is surprisingly absent when the magnetic field is applied along the magnetic easy axis where magnetization is fully saturated. The anisotropy field separating the easy and hard axes is 13 Tesla, unexpected for the Mn ions with nominally negligible orbital momentum and spin-orbit interactions. Double exchange and Jahn-Teller distortions that drive the hole-doped manganites do not exist in Mn3Si2Te6. The phenomena fit no existing models, suggesting a unique, intriguing type of electrical transport.