Large magnetocrystalline anisotropy in tetragonally distorted Heuslers: a systematic study
arXiv:1702.08150 · doi:10.1088/1361-6463/aa5441
Abstract
With a view to the design of hard magnets without rare earths we explore the possibility of large magnetocrystalline anisotropy energies in Heusler compounds that are unstable with respect to a tetragonal distortion. We consider the Heusler compounds FeYZ with Y = (Ni, Co, Pt), and CoYZ with Y = (Ni, Fe, Pt) where, in both cases, Z = (Al, Ga, Ge, In, Sn). We find that for the CoNiZ, CoPtZ, and FePtZ families the cubic phase is always, at , unstable with respect to a tetragonal distortion, while, in contrast, for the FeNiZ and FeCoZ families this is the case for only 2 compounds -- FeCoGe and FeCoSn. For all compounds in which a tetragonal distortion occurs we calculate the MAE finding remarkably large values for the Pt containing Heuslers, but also large values for a number of the other compounds (e.g. CoNiGa has an MAE of -2.11~MJ/m). The tendency to a tetragonal distortion we find to be strongly correlated with a high density of states at the Fermi level in the cubic phase. As a corollary to this fact we observe that upon doping compounds for which the cubic structure is stable such that the Fermi level enters a region of high DOS, a tetragonal distortion is induced and a correspondingly large value of the MAE is then observed.
8 pages, 5 figures