HIGH-FIELD MAGNETIZATION OF SOME MN ALLOYS

We have made high-field magnetization measurements for some Mn alloys: epsilon-Mn3+delta Ga with delta = -0.30, epsilon-(Mn1-xFex)3Sn with x = 0.1 and 0.3, Fe3Mn4Ge6.1 and gamma-(Mn1-xFex)1-yGay with x = 0.44 a nd y = 0.27. The epsilon -Mn3+deltaGa has the hexagonal D0(19) type st ructure and a distorted triangular antiferromagnetic spin structure. T he hexagonal lattice is slightly distorted to an orthorhombic lattice at T(d) of about 290 K with large magnetization. Pseudo-binary epsilon -(Mn1-xFex)3Sn has also the D0(19) type structure, and the alloys with x < 0.4 show coexistence of a triangular antiferromagnetic state and a ferromagnetic state. The triangular spin structure is preserved even in the high field of up to 150 kOe. Ternary alloy Fe3Mn4Ge6.1 has an hp13-type structure, and shows an antiferromagnetism below 470 K. The isothermal magnetization at 77 K shows a steep increase around 110 kOe , suggesting the metamagnetic transition. The gamma-(Mn1-xFex)1-yGay i s face centered cubic. The alloys with x = 0.4 approximately 0.5 and y = 0.27 show coexistence of an antiferromagnetic state and a ferromagn etic state below Neel temperature (T(N) approximately 300K), and a typ ical ferromagnetic behavior above T(N) ( Curie temperature T(C) > 550 K). The magnetization of the coexisting state at 77 K in a field of 15 0 kOe was comparable to that of the ferromagnetic state at 300 K.