- 10月17日 (水), 13:30-
- 京都大学理学部 5号館 413
- Mr. Shuntaro Sumita
- (Condensed Matter Theory Group)
- "Classification of topological crystalline superconducting nodes on high-symmetry line"
Abstract: Recent exact classification of a superconducting gap have elucidated unconventional gap structures [1-8], which have not been predicted by the classification of order parameter based on the point group . One of the important previous results is that all symmetry-protected line nodes on mirror- or glide-invariant planes in the Brillouin zone are characterized by a nontrivial topological number [6, 7]. Another discovery is the novel gap structures depending on the angular momentum of the normal state j_z on threefold and sixfold rotational-symmetric lines [1, 3, 8]. Stimulated by these facts, we classify all crystal symmetry-protected nodes (including such j_z-dependent nodes) on high-symmetry n-fold (n = 2, 3, 4, and 6) axes, by using the combination of group theory and K-theory . As a result, it is shown that the classification by group theory completely corresponds with the topological classification. We also discuss superconducting gap structures in SrPtAs, CeCoIn_5, UPt_3, and UCoGe. Reference:  V. G. Yarzhemsky and E. N. Murav'ev, J. Phys.: Condens. Matter 4, 3525 (1992).  M. R. Norman, Phys. Rev. B 52, 15093 (1995).  V. G. Yarzhemsky, Phys. Status Solidi B 209, 101 (1998).  T. Micklitz and M. R. Norman, Phys. Rev. B 80, 100506 (2009).  T. Nomoto and H. Ikeda, J. Phys. Soc. Jpn. 86, 023703 (2017).  T. Micklitz and M. R. Norman, Phys. Rev. Lett. 118, 207001 (2017).  S. Kobayashi, S. Sumita, Y. Yanase, and M. Sato, Phys. Rev. B 97, 180504 (2018).  S. Sumita and Y. Yanase, Phys. Rev. B 97, 134512 (2018).  M. Sigrist and K. Ueda, Rev. Mod. Phys. 63, 239 (1991).  K. Shiozaki, M. Sato, and K. Gomi, arXiv:1802.06694.