Baromagnetic Effect in the Hexagonal Mn3Sn System

Abstract

The magnetic behaviors influenced by the hydrostatic pressure in the polycrystalline hexagonal Mn3Sn intermetallic compound are briefly reported. The crystalline structure of Mn3Sn is determined to be hexagonal with lattice parameters $a = b = 5.674$ (6) A and $c = 4.533$ (6) A by means of the powder X-ray diffraction and the subsequent Rietveld refinement. Two distinct transitions can be observed from the M(T) curves in the range of 150-450 K. During the cooling process, Mn3Sn sample first changes into a triangular antiferromagnetic (AFM) state with weak ferromagnetism at the Neel temperature of ~412 K, and then, it further transforms to a spiral AFM spin arrangement over a broad temperature range from 260 to 180 K at ambient pressure. With the application or the increase of hydrostatic pressures, this triangular to spiral AFM transition occurs at higher temperatures, while the magnetization of triangular AFM phase increases significantly. Such a phenomenon can be explained by the fact that the hydrostatic pressure compresses the sample and shortens the Mn–Mn separation, and thus, the moments of Mn will deviate from their ideal 120° configuration to their easy axis in the basal plane. The variations of transition temperature and maximum magnetization with applied hydrostatic pressure confirm the incremental instability of the triangular AFM arrangement under pressure.