Fully Compensated Ferrimagnetic Properties of (Cr,Fe)S Compound with a Pyrrhotite-type Structure

Abstract: To optimize the processing conditions for the (Cr,Fe)S non-equilibrium phase with a pyrrhotite-type structure, the phase states and magnetic properties of the specimens obtained at various sintering temperatures were investigated. A slightly off-stoichiometric composition of Cr23Fe23S54 (approximately (Cr,Fe)7S8) sintered and quenched from 1323 K indicates a single-phase pyrrhotite-type structure with a layered-NiAs-type structure in which vacancies occupy every two layers (C12/c1; the space number is 15). The compound shows fully compensated ferrimagnetic behavior at a magnetization compensated temperature of approximately 200 K. The magnetic behavior exhibits a typical N-type ferrimagnet, as predicted by Néel. From X-ray photoelectron spectroscopy analyses, it is found that the compound is composed of Fe2+ and Cr3+. The large magnetic coercivity of 38 kOe at 5 K is also unique and can be applied to spintronic devices. Furthermore, changing the quenching temperature enables control of the degree of order of the vacancies in the interlayer and results in tuning of the magnetization compensated temperature. First-principles calculations show a pseudo-gap located at the Fermi level in the up-spin band, suggesting high spin polarization as well as the NiAs-type structure indicated in the previous our report.