Density functional calculations of the electronic band structure for superconducting and semiconducting metal hexaborides are compared using a consistent suite of assumptions and with emphasis on the physical implicat...Density functional calculations of the electronic band structure for superconducting and semiconducting metal hexaborides are compared using a consistent suite of assumptions and with emphasis on the physical implications of computed models. Spin polarization enhances mathematical accuracy of the functional approximations and adds significant physical meaning to model interpretation. For YB6 and LaB6, differences in alpha and beta projections occur near the Fermi energy. These differences are pronounced for superconducting hexaborides but do not occur for other metal hexaborides.展开更多
Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation （GGA）. The electronic and magnetic properties of Heusler alloys CoaCrZ （Z -- Ga, Ge, As...Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation （GGA）. The electronic and magnetic properties of Heusler alloys CoaCrZ （Z -- Ga, Ge, As） were investigated by using local spin density approximation （LSDA）. Amongst the systems under investigation, CoECrGe and Co2CrGa give I00% spin polarization at the Fermi level （EF）. Co2CrGe and CoECrGa are the most stable half-metallic ferromagnets （HMFs）; their EF lie exactly at the gap of 0.24 eV and 0.38 eV, respectively, in the spin-down channel. Even though CoaCrAs gives a distinct and bigger gap as compared to CoECrGa and CoECrGe, its EF is not located at the middle of the gap in the spin-down channel. We have also found that the total magnetic moments increase as the Z goes from Ga to As. The calculated density of states and band structures show the HMF character for CoECrGe and Co2CrGa.展开更多
文摘Density functional calculations of the electronic band structure for superconducting and semiconducting metal hexaborides are compared using a consistent suite of assumptions and with emphasis on the physical implications of computed models. Spin polarization enhances mathematical accuracy of the functional approximations and adds significant physical meaning to model interpretation. For YB6 and LaB6, differences in alpha and beta projections occur near the Fermi energy. These differences are pronounced for superconducting hexaborides but do not occur for other metal hexaborides.
基金the DST Inspier research fellowship and RKT, a research grant from UGC(New Delhi,India)
文摘Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation （GGA）. The electronic and magnetic properties of Heusler alloys CoaCrZ （Z -- Ga, Ge, As） were investigated by using local spin density approximation （LSDA）. Amongst the systems under investigation, CoECrGe and Co2CrGa give I00% spin polarization at the Fermi level （EF）. Co2CrGe and CoECrGa are the most stable half-metallic ferromagnets （HMFs）; their EF lie exactly at the gap of 0.24 eV and 0.38 eV, respectively, in the spin-down channel. Even though CoaCrAs gives a distinct and bigger gap as compared to CoECrGa and CoECrGe, its EF is not located at the middle of the gap in the spin-down channel. We have also found that the total magnetic moments increase as the Z goes from Ga to As. The calculated density of states and band structures show the HMF character for CoECrGe and Co2CrGa.
