Ab initio study of properties of Co- and Cu- doped Ni-Mn-Ga alloys

Abstract

The influence of Co and Cu doping on Ni-Mn-Ga alloy is investigated using the first-principles exact muffin-tin orbital method in combination with the coherent-potential approximation. The energy difference between the austenite (A) and the nonmodulated (NM) martensite E_A-NM depends linearly on the Cu concentration and distribution, with a minimum for all Cu at Mn sites and a maximum for all Cu at Ga sites. For alloys simultaneously doped by Co in Ni sublattice and Cu in Mn or Ga sublattice, the effects of the individual dopants on E_A-NM and (c/a)_NM and are almost independent. The alloy with composition Ni46Co4Mn24Ga22Cu4 exhibits decreased equilibrium (c/a)_NM and increased E_A-NM in comparison with Ni50Mn25Ga25, which is in agreement with the previous experimental results.The influence of Co and Cu doping on Ni-Mn-Ga alloy is investigated using the first-principles exact muffin-tin orbital method in combination with the coherent-potential approximation. The energy difference between the austenite (A) and the nonmodulated (NM) martensite E_A-NM depends linearly on the Cu concentration and distribution, with a minimum for all Cu at Mn sites and a maximum for all Cu at Ga sites. For alloys simultaneously doped by Co in Ni sublattice and Cu in Mn or Ga sublattice, the effects of the individual dopants on E_A-NM and (c/a)_NM and are almost independent. The alloy with composition Ni46Co4Mn24Ga22Cu4 exhibits decreased equilibrium (c/a)_NM and increased E_A-NM in comparison with Ni50Mn25Ga25, which is in agreement with the previous experimental results.