Structural and magnetic studies on CuMPt6 (M= 3d elements) ternary alloys

Institute of Materials Science, University of Tsukuba
â—‹Ejaz Ahmed Yuji Fuji Miwako Takahashi Hiroshi Iwasaki Ken-ichi Ohshima

We have already identified the crystal structure of newly designed CuMPt6 (M=3d elements) alloys by X-ray, electron and neutron diffraction methods [1, 2]. In the analysis, a double step ordering without any change of cubic symmetry was firstly discovered for CuMnPt6 alloy. In order to obtain more quantitative information on structure and magnetism of the alloys, we have performed in-situ X-ray diffraction, electrical resistivity and magnetic susceptibility measurements. First, the transition temperatures from disordered to Cu3Au type ordered phases were determined in a temperature range from 750 oC for M=Mn to 1010 oC for M=Fe. Secondly, the values of the resistivity were determined as (5~7)x10-5 ohm-cm except for M = Mn with 6x10-4 ohm-cm. Thirdly, a general trend in magnetic properties is as follows: paramagnetic - spinglass like - ferromagnetic - paramagnetic with increasing atomic number. The nature of the magnetism is not much affected by the structural phase changes in the present alloys, though a little change is observed in Tc or Tg due the structural phase change. The original nature of the magnetism in the ternary CuMPt6 alloys remains the same as in the binary MPt3 one. We believe that the unpaired electrons in 3d-elements are responsible for the magnetic properties of CuMPt6 alloys.

[1]. M. Takahashi, A. K. Das, R. Nakamura, H. Iwasaki, T. Shishido and K. Ohshima: J. Phys. Soc. Jpn. 75 (2006) 013601-1.
[2]. A. K. Das, R. Nakamura, M. Takahashi, H. Iwasaki, T. Shishido and K. Ohshima: J. Phys. Soc. Jpn. 75 (2006) 024604.