1,978 research outputs found
Theory for superconductivity in alkali chromium arsenides A2Cr3As3 (A=K,Rb,Cs)
We propose an extended Hubbard model with three molecular orbitals on a
hexagonal lattice with symmetry to study recently discovered
superconductivity in ACrAs (A=K,Rb,Cs). Effective pairing
interactions from paramagnon fluctuations are derived within the random phase
approximation, and are found to be most attractive in spin triplet channels. At
small Hubbard and moderate Hund's coupling, the pairing arises from
3-dimensional (3D) band and has a spatial symmetry
, which gives line nodes in the gap function. At large
, a fully gapped -wave state, dominates at the quasi-1D
-band
Symmetry of superconducting states with two orbitals on a tetragonal lattice: application to
We use group theory to classify the superconducting states of systems with
two orbitals on a tetragonal lattice. The orbital part of the superconducting
gap function can be either symmetric or anti-symmetric. For the orbital
symmetric state, the parity is even for spin singlet and odd for spin triplet;
for the orbital anti-symmetric state, the parity is odd for spin singlet and
even for spin triplet. The gap basis functions are obtained with the use of the
group chain scheme by taking into account the spin-orbit coupling. In the weak
pairing limit, the orbital anti-symmetric state is only stable for the
degenerate orbitals. Possible application to iron-based superconductivity is
discussed.Comment: published versio
Giant mesoscopic spin Hall effect on surface of topological insulator
We study mesoscopic spin Hall effect on the surface of topological insulator
with a step-function potential. The giant spin polarization induced by a
transverse electric current is derived analytically by using McMillan method in
the ballistic transport limit, which oscillates across the potential boundary
with no confinement from the potential barrier due to the Klein paradox, and
should be observable in spin resolved scanning tunneling microscope.Comment: 5 pages, 3 figure
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