Magnetization and magnetic phase diagram of Heusler compounds Fe_(3-y)(Mn_(1-x)V_x)_ySi (y = 1 and 1.5)

摘要

Fe_2MnSi exhibits a ferromagnetic transition at T_C and another transition to a phase with antiferromagnetic components at a low temperature of T_A. By substituting V for Mn, so as to obtain Fe_2Mn_(1-x)V_xSi, T_A decreases with x and then vanishes around x ～ 0.2. In this study, the magnetic transitions are investigated by magnetization measurements for Fe_2Mn_(1-x)V_xSi (y = 1, 0 ≤ x ≤ 0.2) in high magnetic fields up to ～70 T and for Fe_(1.5)(Mn_(1-x)V_x)_(1.5)Si (y = 1.5, 0 ≤ x ≤ 0.1) up to 5 T. For y = 1.5, with increasing x, T_C increases and T_A decreases as for y = 1, and the rate of the decrease in T_A with x is slightly smaller than for y=1. In the low magnetic field region, T_A for y = 1 does not significantly change due to the magnetic field but a distinct decrease is observed in high fields. The critical field at 0 K of this transition in Fe_2MnSi is found to be larger than 70 T, and with increasing x, the critical field decreases corresponding to the decrease of T_A at zero field.