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We study a local antisymmetric spin-orbit (ASO) coupling effect on a triangular-triple-quantum-dot (TTQD) system as a theoretical proposal for a new application of the Kondo physics to nanoscale devices. The electric polarization induced by the Kondo effect is strongly correlated with the spin configurations and molecular orbital degrees of freedom in the TTQD. In particular, an abrupt sign reversal of the emergent electric polarization is associated with a quantum critical point in a magnetic field, which can also be controlled by the ASO coupling that changes the mixing weight of different orbital components in the TTQD ground state.

We investigate exciton-mediated triplet superconductivity in a T h system PrOs4Sb12 and discuss a twofold symmetry of the gap function corresponding to the lower magnetic field phase.

Cu 3 ( CO 3 ) 2 ( OH ) 2 is a new compound consisting of diamond shaped spin chains. Magnetization measurements revealed a plateau at 1 3 of the saturated moment. This feature together with the magnetic excitations observed by high-field electron spin resonance (ESR) measurements can be understood as a model of coupled spin dimer and monomer system. We present a theory for the magnetic excitations of this system based on an extended bond-operator theory, and discuss the field dependence of the observed excitation modes by the ESR measurements.

The local density of states of quasi-particles, N(E,r), around columnar defects generated by bombardment of high-energy heavy ions parallel to the c-axis in Bi2Sr2CaCu2Ox (Bi-2212) and 2H-NbSe2 has been studied by scannning tunneling spectroscopy at 4.2 K and compared. The regions of columnar defects have been found to be insulating and circular superconductor–insulator boundaries have been studied. In Bi-2212 the N(E,r) has exhibited the increase at E=0 meV and the decrease at E∼35 meV at [1 1 0] and [ 1 1 0] directions in CuO2 square network and seems to show the pattern with four-fold symmetry, while in 2H -NbSe2 such things have not been observed. This is new evidence of the presence of dx2–y2 component in the order parameter of Bi-2212.

The chiral optical absorption by a single vortex in a p_x \pm i p_y-wave superconductor is studied theoretically. The p_x \pm i p_y-wave state was recently suggested as the symmetry of the order parameter of Sr_2 Ru O_4 superconductor. Due to the violation of time reversal symmetry, there are two types of vortices whose winding orientation is the same or opposite to the angular momentum of the Cooper pair. In a real material domains with p_x \pm i p_y-wave states are expected. However, optical absorption of circular polarized light depends only on the winding of the vortex and has a low energy absorption peak which results in dichroism. Dichroism occurs if superconductivity is realized on a single Fermi surface sheet. However, in the case of several Fermi surface sheets dichroism may disappear, if the both types of carriers are present, electron-like and hole-like. Therefore chiral optical absorption is a possible experiment to detect the orbital dependent superconductivity which was suggested as the superconducting state of Sr_2 Ru O_4.

The microscopic mechanism of circular currents induced in the vicinity of a non-magnetic impurity is analyzed for the (time-reversal symmetry breaking) chiral superconducting state d ( k )= z (k x ± i k y ) which is very likely realized in Sr2RuO4. From the analytic, not self-consistent solution of the Bogolyubov–de Gennes equations we find two types of quasiparticle states, a bound state and the continuum state. Through impurity scattering the condensate transfers angular momentum to the quasiparticle states which generate a circular current.