Magnetic properties of the off-stoichiometric Heusler alloys Rh2Mn1+xSn1-x

Abstract

We report the results of experimental investigation of the crystal structure, magnetization and 119Sn Mössbauer spectroscopy of Rh2Mn1+xSn1-x (0 ≤ x ≤ 0.6). The samples crystallize in the cubic L21-type structure for 0 ≤ x ≤ 0.4 and the cubic B2-type structure for x = 0.5 and 0.6. X-ray diffraction patterns with the samples with 0 ≤ x ≤ 0.4 indicate that the excess Mn atoms occupy the Sn sites. The samples with 0 ≤ x ≤ 0.4 exhibit the typical ferromagnetic behavior. The magnetic moment at 5 K of 4.27 μB/f.u. for x = 0 (Rh2MnSn) initially increases with increasing x and saturates for x ≥ 0.2. On the other hand, the Curie temperature for 0 ≤ x ≤ 0.4 decreases with increasing x. It is presumed that both samples with x = 0.5 and 0.6 are in the heterogeneous magnetic state. The 119Sn Mössbauer spectroscopy measurements showed that the hyperfine field at 90 K for 0 ≤ x ≤ 0.6 increases with increasing x. The concentration dependence of the magnetic moment and the Curie temperature for Rh2Mn1+xSn1-x (0 ≤ x ≤ 0.6) are discussed qualitatively based on the Mn-Rh and Mn-Mn interactions in the crystal.