Nearly degenerate px+ipy and dx2-y2 pairing symmetry in the heavy fermion superconductor YbRh2⁢Si2

Release time:2019-08-20  Hits:

• DOI number:10.1103/PhysRevB.100.085132
• Journal:Physical Review B
• Abstract:Recent discovery of superconductivity in YbRh2⁢Si2 has raised particular interest in its pairing mechanism and gap symmetry. Here we propose a phenomenological theory of its superconductivity and investigate possible gap structures by solving the multiband Eliashberg equations combining realistic Fermi surfaces from first-principles calculations and a quantum critical form of magnetic pairing interactions. The resulting gap symmetry shows sensitive dependence on the in-plane propagation wave vector of the quantum critical fluctuations, suggesting that superconductivity in YbRh2⁢Si2 is located on the border of (����+��⁢����) and ����2−��2-wave solutions. This leads to two candidate phase diagrams: one has only a spin-triplet (����+��⁢����)-wave superconducting phase; the other contains multiple phases with a spin-singlet ����2−��2-wave state at zero field and a field-induced spin-triplet (����+��⁢����)-wave state. In addition, the electron pairing is found to be dominated by the “jungle-gym” Fermi surface rather than the “doughnut”-like one, in contrast to previous thought. This requests a more elaborate and renewed understanding of the electronic properties of YbRh2⁢Si2.
• Indexed by:Journal paper
• Translation or Not:no
• Date of Publication:2019-01-01
• Links to published journals:https://journals.aps.org/prb/abstract/10.1103/PhysRevB.100.085132