Wei-Cheng Lee

Pairing state with a time-reversal symmetry breaking in FeAs-based superconductors

We investigate the competition between the extended s+/--wave and dx2-y2-wave pairing order parameters in the iron-based superconductors. Because of the frustrating pairing interactions among the electron and the hole Fermi pockets, a time-reversal symmetry breaking s+id pairing state could be favored. We analyze this pairing state within the Ginzburg-Landau theory and explore the experimental consequences. In such a state, spatial inhomogeneity induces a supercurrent near a nonmagnetic impurity and the corners of a square sample. The resonance mode between the s+/-- and dx2-y2-wave order parameters can be detected through the B1g Raman spectroscopy.

Quasiparticle interference on the surface of the topological insulator Bi 2 Te 3

The quasiparticle interference of the spectroscopic imaging scanning tunneling microscopy has been investigated for the surface states of the large gap topological insulator Bi

Theory of unconventional metamagnetic electron states in orbital band systems

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Frustrated Cooper pairing and f-wave supersolidity in cold-atom optical lattices

Te

Unconventional metamagnetic electron states in orbital band systems

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Quasiparticle interference on the surface of the topological insulatorBi2Te3

through the T-matrix formalism. Both the scalar potential scattering and the spin-orbit scattering on the warped hexagonal isoenergy contour are considered. While backscatterings are forbidden by time-reversal symmetry, other scatterings are allowed and exhibit strong dependence on the spin configurations of the eigenfunctions at k points over the isoenergy contour. The characteristic scattering wavevectors found in our analysis agree well with recent experiment results.

Quasiparticle Interference on the Surface of the Topological Insulator Bi

We extend the study of the Fermi surface instability of the Pomeranchuk type into systems with orbital band structures, which are common features in transition metal oxides. Band hybridization significantly shifts the spectral weight of the Landau interactions from the conventional

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s

Te

-wave channel to unconventional non-

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s