Surface state of the interorbital pairing state in the Sr2RuO4 superconductor

We study the (001) surface state of a recently proposed ${E}_{g}$ symmetry interorbital-odd spin-triplet $s$-wave superconducting (SC) state in ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$. We confirm that this pair potential is transformed into a chiral $d$-wave pair potential and a pseudo-Zeeman field in the band basis for a low-energy range. Because of the chiral $d$-wave pair potential, the surface states appear near zero energy in the momentum range enclosed by the nodal lines of the chiral $d$-wave pair potential for each band at the (001) surface. Nevertheless, the pseudo-Zeeman field gives band splitting of the surface states, and its splitting energy is much smaller than the SC energy gap. The local density of states (LDOS) at the (001) surface of the SC state has a pronounced peak structure at zero energy because of the surface states near zero energy when the order of the resolution is lower than the splitting energy. This peak structure is robust against perturbations, such as an orbital Rashba coupling or an ${E}_{u}$ SC pair potential at the surface.