Magnetic properties of Heusler alloy Mn2RuGe and Mn2RuGa ribbons

Heusler alloys Mn2RuGe and Mn2RuGa have been prepared by melt-spinning method successfully. Theoretical and experimental studies reveal a ferrimagnetic ground state in the two alloys. The Curie temperatures are 303 K for Mn2RuGe and 272 K for Mn2RuGa. The calculated total spin moments of Mn2RuGe and Mn2RuGa are integral values of 2.00 mu(B) and 1.03 mu(B), respectively. And the theoretical spin polarization ratio is also quite high. However, due to the atomic disorder in the ribbons, the saturation moments of them measured at 5 K are smaller than the calculated values, especially that of Mn2RuGa. This coincides with the disappearance of the superlattice reflection (111) and (200) peaks in the XRD pattern of Mn2RuGa. Annealing Mn2RuGa ribbon at 773 K can enhance the atomic ordering. Both saturation magnetic moment and Curie temperature increase obviously after the heat treatment. (C) 2014 Elsevier B.V. All rights reserved.