Structure and magnetic properties of Fe2CoGe synthesized by ball-milling

A Heusler alloy Fe2CoGe has been synthesized by the ball-milling method. Its structure and magnetic properties have been studied. The results suggest that ball-milling can be a possible way to produce new Heusler alloys. Both X-ray diffraction and DTA measurement evidenced the formation of a partly amorphous phase after milling for 25 h. It is found that highly ordered Fe2CoGe can be obtained by annealing the as-milled powder at 1073 K, while a disordered A2 phase is resulted by annealing at 773 K. The magnetic properties of Fe2CoGe are not very sensitive to the atomic disorder. Electronic structure calculation suggests a ferromagnetic ground state in highly ordered Fe2CoGe and the total spin moment is 5.03μB/f.u., which agrees well with the experimental value of 5.06μB for the sample annealed at 1073 K. It is also found that the atomic disorder does not strongly change the ferromagnetic coupling between Fe and Co moments and also the general structure of the DOS. So the total spin moment only slightly increases when atomic disorder occurs.