PECULIAR OPTICAL PROPERTIES OF Co2MnGa ALLOYS

Joo Yull Rhee (BK21 Physics Research Division and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746)
Y.V. Kudryavtsev (Institute of Metal Physics, National Academy of Sciences of Ukraine, 36 Vernadsky Str., 03142, Kiev-142,)
K.W. Kim (Department of Physics, Sunmoon University, Asan 336-708)
Y.P. Lee (q-Psi and Department of Physics, Hanyang University, Seoul 133-791)

ASEAN Journal on Science and Technology for Development
Vol. 24 No. 1-2 (2007): ASEAN Journal on Science and Technology for Development (AJSTD)

Co2MnGa alloy was prepared by the conventional arc-melting method. The optical conductivity (OC) spectrum of the alloy was measured by a rotating-analyzer spectroscopic ellipsometer. The OC spectrum was also calculated based on the electronic structure by using the full-potential linearized-augmented-plane-wave method within the local-spin-density approximation to the density-functional theory. The calculated OC spectrum does not agree well with the experimental one. Since the Co2MnGa alloy could be a strongly-correlated material, the so-called 'LDA+U' method was applied with U = 5.4 eV. The calculated OC spectrum using the 'LDA+U' method agrees very well with the experimental one. The inclusion of the onsite Coulombpotential during the self-consistent calculation significantly modifies the minorityspin Co and Mn 3d bands, resulting in a contraction of the energy gaps between states which are strongly involved in interband absorption peaks.