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We investigate the rotation effect of the RuO$_6$ octahedron around the $c$ axis on the topological and transport properties near the surface of the spin-triplet superconductor Sr$_2$RuO$_4$. While the Fermi level of bulk Sr$_2$RuO$_4$ is near the Lifshitz transition, the RuO$_6$ rotation realized near the surface leads to the change of the Fermi surface topology. The edge current resulting from the time-reversal symmetry breaking in the chiral $p$-wave phase with fully opened excitation gap is less affected around Lifshitz transition. The topological property and the edge state are sensitive to the rotation angle and the amplitude of the nearest neighbor interaction, and the superconducting gap is strongly reduced in the larger next nearest neighbor interaction region. Although the edge state in Sr$_2$RuO$_4$ is topologically protected, it is not robust to the disorder such as impurity or defect.
High resolution angle-resolved photoemission measurements are carried out to systematically investigate the effect of cleaving temperature on the electronic structure and Fermi surface of Sr$_2$RuO$_4$. Different from previous reports that high cleav
SrRuO3 is a ferromagnetic metal with several unusual physical properties such as zero thermal expansion below Tc, so-called Invar behavior. Another anomalous feature is that the a-axis lattice constant is larger than the b-axis lattice constant, a cl
We study bulk electronic states of superconducting topological insulator, which is the promising candidate for topological superconductor. Recent experiments suggest that the three-dimensional Fermi surface evolves into two-dimensional one. We show t
Although Sr3Ru2O7 has not been reported to exhibit superconductivity so far, ac susceptibility measurements revealed multiple superconducting transitions occurring in the Sr3Ru2O7 region cut from Sr3Ru2O7-Sr2RuO4 eutectic crystals. Based on various e
We report enhancement in the magnetic critical current density of indium added polycrystalline SmFeAsO1-xFx. The value of magnetic Jc is around 25 kA/cm2 at 4.2 K under self-magnetic field. Polycrystalline SmFeAsO1-xFx is mainly composed of the super