Electronic band structure and fermi surface of heavy-fermion neptunium superconductor NpPdAl

重い電子系ネプツニウム化合物超伝導体NpPdAlのバンド構造とフェルミ面

山上 浩志*; 青木 大*; 芳賀 芳範   ; 大貫 惇睦

Yamagami, Hiroshi*; Aoki, Dai*; Haga, Yoshinori; Onuki, Yoshichika

Electronic band structure calculations were carried out for a new neptunium superconductor NpPdAl using a relativistic linear-augmented plane wave method within a local density approximation. The Fermi energy in the band structure is found to be located just on the 5f -bands of the j = 5/2 state with the extremely narrow band width and therefore the theoretical electronic specific heat coefficient is extremely large, being =74.0mJ/Kmol, which is compared to =390 estimated experimentally. NpPdAl is an uncompensated metal. The main electron Fermi surface corresponds to a doughnut-like flat Fermi surface centered at the point which is connected with cylindrical Fermi surfaces elongated along the X-W-P line.