Theoretical study of half-metallicity in the bulk and (001) oriented thin-films of the CoMn1-xFexCrAl and CoMn1-xCoxCrAl (x=0.00, 0.25, 0.50, 0.75 or 1.00) Heusler alloys

Abstract

We theoretically investigate the structure, electronic and magnetic properties of the pristine bulk CoMnCrAl Heusler alloy and its (110), (111) and (001) oriented thin-films by using first-principles calculations. We find that the pristine bulk CoMnCrAl Heusler alloy has 100.00% spin-polarization (SP) and half-metallic (HM) character. We also find that the CoMnCrAl-terminated (110) oriented thin-film is nearly half-metal due to its high SP and the CrAl-terminated (001) oriented thin-film maintains the HM character due to 100.00% SP at the Fermi level EF. We also study the structural, electronic and magnetic properties of the Fe or Co doped bulk CoMn1‒xFexCrAl and CoMn1‒xCoxCrAl (x = 0.25, 0.50, 0.75 or 1.00) Heusler alloys and their CrAl-terminated (001) oriented thin-films. All the bulk systems and their CrAl-terminated (001) oriented thin-films show half-metallicity and 100% SP. The spin-down bandgaps Eg↓of the CrAl-terminated (001) oriented thin-films of the Fe or Co doped systems are all lager than that of the CrAl-terminated (001) oriented thin-film of the pristine bulk CoMnCrAl Heusler alloy, implying that the HM character of the Fe or Co doped systems are more stable.