We show from a weak coupling microscopic calculation that the most favored chiral superconducting order parameter in Sr2RuO4 has Chern number |C|=7. The two dominant components of this order parameter are given by sin(3 kx) + i sin(3 ky) and sin(kx) cos(ky) + i sin(ky) cos(kx) and lie in the same irreducible representation Eu of the tetragonal point group as the usually assumed gap function sin(kx) + i sin(ky). While the latter gap function leads to C=1, the two former lead to C=-7, which is also allowed for an Eu gap function since the tetragonal symmetry only fixes C modulo 4. Since it was shown that the edge currents of a |C|>1 superconductor vanish exactly in the continuum limit, and can be strongly reduced on the lattice, this form of order parameter could help resolve the conflict between experimental observation of time-reversal symmetry breaking and yet the absence of observed edge currents in Sr2RuO4.
Cite
@article{arxiv.1410.6073,
title = {Large Chern Number and Edge Currents in Sr2RuO4},
author = {Thomas Scaffidi and Steven H. Simon},
journal= {arXiv preprint arXiv:1410.6073},
year = {2015}
}
Comments
5 pages, 2 figures; Spin-orbit-coupled three-orbital BdG calculation added; Accepted for publication in Physical Review Letters