Large magnetocrystalline anisotropy in tetragonally distorted Heuslers: a systematic study

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 Fe2YZ with Y = (Ni, Co, Pt), and Co2YZ with Y = (Ni, Fe, Pt) where, in both cases, Z = (Al, Ga, Ge, In, Sn). We find that for the Co2NiZ, Co2PtZ, and Fe2PtZ families the cubic phase is always, at T = 0, unstable with respect to a tetragonal distortion, while, in contrast, for the Fe2NiZ and Fe2CoZ families this is the case for only 2 compounds -Fe2CoGe and Fe2CoSn. 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. Co2NiGa has an MAE of -2.11 MJ/m 3 ). 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.PACS numbers:

Pressure dependent half-metallic ferromagnetism in inverse Heusler alloy Fe2CoAl: a DFT+U calculations

“…2c and d. The calculated lattice constant is 5.73Å and is consistent with previously reported values of 5.70Å, 73 5.71Å, 74 5.766 AE 0.05Å, 75 and 5.732Å. 76 This result also agrees well with the results for several other analogous Fe-based inverse Heusler alloys whose lattice parameters vary from 5.5 to 6.2Å.…”

Epitaxial Fe3O4 Films Grown on R-Plane Sapphire by Pulsed Laser Deposition

“…Note first of all that a substrate can determine the type of crystal lattice. In the case of complex lattices, characteristic of half-metals, this is critical [2] because changes in the type of lattice can cause the material to lose properties of a halfmetal. Magnetite has a cubic lattice (inverse spinel structure), so the (001) crystallographic orientation of Fe 3 O 4 films is of most interest for practical applications.…”

Competition between cubic and tetragonal phases in all-d-metal Heusler alloys, X 2−x Mn1+x V (X = Pd, Ni, Pt, Ag, Au, Ir, Co; x = 1, 0): a new potential direction of the Heusler family

“…However, tetragonal phases are more likely to demonstrate large perpendicular magnetic anisotropy than the cubic statethe key to spin-transfer torque devices (Balke et al, 2007). Additionally, tetragonal states have large magneto-crystalline anisotropy (Salazar et al, 2018;Matsushita et al, 2017), large intrinsic exchange-bias behaviour (Felser et al, 2013;Nayak et al, 2012) and a high Curie temperature. To better apply Heusler alloys to actual fields, it is also important to study their tetragonal state and the competition between cubic and tetragonal states.…”