On Berry Phase in Bloch States

We comment on the relation between Berry phase and quantized Hall conductivities for charge and spin currents in some Bloch states, such as Bloch electrons in the presence of electromagnetic fields and quasiparticles in the vortex states of superfluid $^3$He. One can find out that the arguments presented here are closely related to the spontaneous polarization in crystalline dielectrics and the adiabatic pumping.Comment: 2 pages, 1 figure, to be published in the proceedings of LT23 in Hiroshima, Aug. 200

Meissner effect in the layered Kane-Mele model with Hubbard interaction

We investigate the magnetic response in the quantum spin Hall phase of the layered Kane-Mele model with Hubbard interaction, and argue a condition to obtain the Meissner effect. The effect of Rashba spin orbit coupling is also discussed.Comment: 4 pages, accepted for publication in Journal of Physics: Conference Series as proceedings of International Symposium "Nanoscience and Quantum Physics 2011" (nanoPHYS'11) held in Toky

Intrinsic and extrinsic origins of the polar Kerr effect in a chiral p-wave superconductor

Recently, the measurement of the polar Kerr effect (PKE) in the quasi two-dimensional superconductor Sr2RuO4, which is motivated to observe the chirality of px + i py-wave pairing, has been reported. We clarify that the PKE has intrinsic and extrinsic (disorder-induced) origins. The extrinsic contribution would be dominant in the PKE experiment.Comment: 7 pages, to be published in Mod. Phys. Lett.

Deconfinement of Vortices with Continuously Variable Fractions of the Unit Flux Quanta in Two-Gap Superconductors

We propose a new stage of confiment-decofinment transition, which can be observed in laboratory. In two-gap superconductors (SCs), two kinds of vortex exist and each of them carries a continuously variable fraction of the unit flux quanta Phi_0=h c / 2 e. The confined state of these two is a usual vortex and stable in the low temperature region of the system under a certain magnetic field above H_c1. We see an analogy to quarks in a charged pion. An entropy gain causes two fractional vortices to be deconfined above a certain temperature.Comment: 5 pages, 3 figures, to be published in Europhys. Let