The structural and magnetic properties of Ni2Mn1-xMxGa (M=Co, Cu) -: art. no. 10M304

In Ni2MnGa (cubic structure of L2(1) type) a first order martensitic structural transition, from the parent cubic (austenitic) phase to a low temperature complex tetragonal structure, takes place at T-M=202 K, and ferromagnetic order in the austenitic phase sets at T-C=376 K. In this work, the Mn sites in Ni2MnGa have been partially substituted with magnetic Co and nonmagnetic Cu, and the influence of these substitutions on the structural and magnetic properties of Ni2Mn1-xMxGa (M =Co and Cu) have been studied by XRD and magnetization measurements. X-ray diffraction patterns indicate that the Co doped system possess a highly ordered Heusler alloy L2(1) type structure for 0.05 < x < 0.12, and the Cu doped compounds possess L2(1) structure for 0.05 < x < 0.10. The ferromagnetic ordering temperature increases with increasing Co concentration for this system, and rapidly decreases with increasing Cu concentration. Both systems show the increase in T-M with increasing Co and Cu concentration. (T-x) phase diagrams have been plotted. The results are discussed in terms of 3d-electron concentration variation. (c) 2005 American Institute of Physics.