層状金属間化合物Gd1-xLaxMn2Ge2の特異な磁性と伝導現象(I) −リエントラント·フェリ磁性の出現−

In this paper, we report experimental results on the overall magnetic properties of intermetallic compounds Gd1-xLaxMn2Ge2 (0≤x≤1.0) with a ThCr2Si2-type layered structure. In GdMn2Ge2, a first order transition was observed from antiferromagnetic to ferrimagnetic state at Tt3 below TN with decreasing temperature, while in Gd1-xLaxMn2Ge2 with x = 0.075 and 0.050, two kinds of first-order transitions, from ferrimagnetic to antiferromagnetic and from antiferromagnetic to reentrant ferrimagnetic states were observed at Tt2 and Tt3 after they become ferrimagnetic below Tt1. As x further increases canted ferrimagnetism appears with a compensation temperature in all the ordering temperature regions for 0.10 0.50. The compensation behavior as a function of temperature is discussed on the basis of the two-sublattice molecular-field model.