Correlation between the superconducting pairing symmetry and magnetic anisotropy in f-electron unconventional superconductors

Abstract

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. Effectively, there are three categories: 1) In antiferromagnetic systems, unconventional superconductivity appears with singlet (d-wave) pairing or mixed-parity pairing (in non-centrosymmetric compounds) for cases of XY anisotropy. 2) In ferromagnetic systems, unconventional superconductivity with triplet (e.g. p-wave) pairing appears for cases of Ising anisotropy. 3) A few exceptional cases: The origin of the observed correlation will be discussed in terms of the orbital f-electron states.