Spin Fluctuation, Orbital States and Non-conventional Superconductivity in Actinides Compounds

In d-wave unconventional superconductors, superconducting Cooper pairs are believed to be formed via magnetic fluctuations. In fact, the superconducting transition temperature Tc roughly correlates with the antiferromagnetic spin fluctuation energy in d-wave unconventional superconductors including high Tc cuprates. In addition to this correlation, the superconducting pairing symmetry and the magnetic anisotropy of the normal state are found empirically to be strongly correlated in f-electron unconventional superconductors having crystallographic symmetry lower than cubic. In antiferromagnetic systems, unconventional superconductivity appears with singlet (d-wave) pairing for cases of XY anisotropy. In contrast, in ferromagnetic systems, unconventional superconductivity with triplet (e. g. p-wave) pairing appears for cases of Ising anisotropy. In this report, the d-wave case is addressed, the origin of XY anisotropy is discussed in terms of the orbital character; and the angular momentum character jz for each piece of Fermi surfaces is determined.