189 research outputs found

    Wigner crystal of a two-dimensional electron gas with a strong spin-orbit interaction

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    The Wigner-crystal phase of two-dimensional electrons interacting via the Coulomb repulsion and subject to a strong Rashba spin-orbit coupling is investigated. For low enough electronic densities the spin-orbit band splitting can be larger than the zero-point energy of the lattice vibrations. Then the degeneracy of the lower subband results in a spontaneous symmetry breaking of the vibrational ground state. The 6060^{\circ}-rotational symmetry of the triangular (spin-orbit coupling free) structure is lost, and the unit cell of the new lattice contains two electrons. Breaking the rotational symmetry also leads to a (slight) squeezing of the underlying triangular lattice.Comment: 5 pages + appendix, 3 figures, minor improvements to the tex

    Spectrum of the Andreev Billiard and Giant Fluctuations of the Ehrenfest Time

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    The density of states in the semiclassical Andreev billiard is theoretically studied and shown to be determined by the fluctuations of the classical Lyapunov exponent λ\lambda. The rare trajectories with a small value of λ\lambda give rise to an anomalous increase of the Ehrenfest time τEln/λ\tau_E\approx |\ln\hbar|/\lambda and, consequently, to the appearance of Andreev levels with small excitation energy. The gap in spectrum is obtained and fluctuations of the value of the gap due to different positions of superconducting lead are considered.Comment: 4 pages, 3 figure
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