Neutron diffraction study of the fluctuation driven Colossal Magnetoresistance Mn₃Si₂Te₆

Colossal magnetoresistance (CMR) is of great fundamental and technological significance and exists in a number of materials including the most studied manganites. Similar CMR effect was recently observed in the stoichiometric Mn₃Si₂Te₆ that is starkly different from other reported materials. The resistivity drops by orders of magnitude leading to an insulator-metal transition with an applied magnetic field above 9 T. The CMR occurs only when the field is applied along the hard axis, while such effect is conspicuously absent with the field applied in the basal plane, where magnetization is fully saturated. Neutron diffractions are used to characterize the ground state spin structure in zero and applied field along the c-axis. A prominent magnetic diffuse scattering is observed well above the magnetic transition. The relevance of the spin fluctuation is discussed in the context of magnetic polaron model where the CMR effect is directly associated with the suppression of the critical magnetic fluctuation.