Ordering in spatially anisotropic triangular antiferromagnets

We investigate the phase diagram of the anisotropic spin-1/2 triangular lattice antiferromagnet, with interchain diagonal exchange J' much weaker than the intrachain exchange J. We find that fluctuations lead to a competition between (commensurate) collinear antiferromagnetic and (zig-zag) dimer orders. Both states differ in symmetry from the spiral order known to occur for larger J', and are therefore separated by quantum phase transitions from it. The zero-field collinear antiferromagnet is succeeded in a magnetic field by magnetically-ordered spin-density-wave and cone phases, before reaching the fully polarized state. Implications for the anisotropic triangular magnet Cs_2CuCl_4 are discussed.Comment: 4 pages, 2 figures; v2: improved zero-field phase diagram, new figure

Spin-orbit induced spin-density wave in a quantum wire

We present analysis of the interacting quantum wire problem in the presence of magnetic field and spin-orbit interaction. We show that an interesting interplay of Zeeman and spin-orbit terms, facilitated by the electron-electron interaction, results in the spin-density wave (SDW) state when the magnetic field and spin-orbit axes are orthogonal. This strongly affects charge transport through the wire: with SDW stabilized, single particle backscattering off an nonmagnetic impurity becomes irrelevant. Sensitivity of the effect to the direction of the magnetic field can be used for experimental verification of this proposal.Comment: 4.1 pages, 1 figure; v2: published versio