First-principles prediction of the half-metallicity in quaternary Heusler CoRhCrAl thin films

Abstract

Magnetic thin films are essential building blocks for spintronic devices. Whether the spin-dependent properties associated with a parental bulk can be preserved at the surface or interface with a lowered symmetry represents an important topic to be addressed. In the work, theoretical calculations are performed to study the structural, electronic and magnetic properties of the bulk CoRhCrAl quaternary Heusler alloy and its (111)-, (001)- and (110)-oriented thin films by using the VASP package based on the first-principles density functional theory. Our results indicate that the bulk structure of CoRhCrAl alloy is half-metallic (HM) in character with 100% spin-polarization, and its spin-down bandgap and total magnetic moment are eV and 3.00 μ B, respectively. For the thin film structures with different orientations and terminations, half-metallicity only exists in the (111)-oriented thin film with Al-termination, but is lost in the Co-, Rh- or Cr-terminations. On the other hand, both the (001)- and (110)-oriented thin films are partially or nearly HM. Interestingly, the half-metallicity is lost on introducing U parameter in the calculations.