STUDY OF THE MN-MOMENT INSTABILITY IN THE TBMN2 INTERMETALLIC COMPOUND BY SUBSTITUTIONS OF FE FOR MN

The spontaneous volume expansion and anisotropic distortion of the crystal cell in the Tb(Mn1-xFex)2 (x less-than-or-equal-to 0.3) system have been measured in the 5-300 K temperature range. When x greater-than-or-equal-to 0.02 the large positive volume anomaly observed in TbMn2 disappears, indicating a rapid change of the type of magnetic ordering in the Mn subsystem. A single crystal study of Tb(Mn0.96Fe0.04)2 shows up that the easy magnetization direction is the <111> axis in agreement with the rhombohedral distortion.