Electron band structure of antiferromagnetic γ-manganese

A calculation of the electron energy bands for antiferromagnetic γ-manganese arising from the 3d and 4s levels in the free atom has been carried out by the augmented plane wave and Hubbard's parametrized methods, obtaining good agreement between them. The bands for face-centred cubic Mn are split by the tetragonality and there is further exchange splitting due to the antiferromagnetism. The general picture is of two d bands, not completely separated and crossed by a nearly-free-electron band. The width of either d band is similar 0.3 ryd and the Fermi level occurs just above the dip between the bands, giving a value of 0.0033 J mole -1 deg K -2 for the electronic specific heat co-efficient γ, comparable with the experimental values obtained by extrapolation from high temperatures and from alloys but considerably smaller than the only direct measurements for γ-Mn. The calculation gives an estimated value for the atomic moment of 2.4 7 μ B in good agreement with experiment.