5,729 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
Bose-Einstein condensation in strong-coupling quark color superconductor near flavor SU(3) limit
Near the flavor SU(3) limit, we propose an analytical description for
color-flavor-locked-type Bardeen-Cooper-Schrieffer (BCS) phase in the Nambu
Jona-Lasinio (NJL) model. The diquark behaviors in light-flavor and
strange-flavor-involved channels and Bose-Einstein condensation (BEC) of bound
diquark states are studied. When the attractive interaction between quarks is
strong enough, a BCS-BEC crossover is predicted in the environment with
color-flavor-locked pairing pattern. The resulting Bose-Einstein condensed
phase is found to be an intergrade phase before the emergence of the
previous-predicted BEC phase in two-flavor quark superconductor.Comment: 15 pages, 5 figures; 2nd versio
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