Neutron as a probe to study magnetization reversal in a spinel compound, CoCr1.9Fe0.1O4

Neutron depolarization and neutron diffraction techniques have been employed to investigate the origin of magnetization reversal in CoCr1.9Fe0.1O4 spinel compound. The spinel compound crystallizes in a face centered cubic (space group: Fd-3m) structure where Co2+ and (Cr/Fe)(3+) ions occupy the tetrahedral 8a and octahedral 16d sites, respectively. The temperature dependent magnetization curves for magnetic fields < 1 kOe show a magnetization reversal below the compensation temperature (T-comp similar to 40 K). The neutron depolarization measurements infer that the average magnetization of each domain becomes negligibly small at the T-Comp. Temperature dependent neutron diffraction study, a microscopic tool to understand sublattice magnetization, infers an antiparallel coupling between the tetrahedral (Co) and octahedral (Cr/Fe) site moments with ordered magnetic moments of -3.1(1) and 1.0(1) mu(B), respectively, at 30 K. Our neutron diffraction study also reveals that the unequal growth of the antiferromagnetically coupled tetrahedral and octahedral site moments across the T-Comp plays an important role in realizing the magnetization reversal in this spinel compound.