628 research outputs found
Topological phases, topological flat bands, and topological excitations in a one-dimensional dimerized lattice with spin-orbit coupling
The Su-Schrieffer-Heeger (SSH) model describes a one-dimensional
topological insulator, which has two topological distinct phases corresponding
to two different dimerizations. When spin-orbit coupling is introduced into the
SSH model, we find the structure of the Bloch bands can be greatly changed, and
most interestingly, a new topological phase with single zero-energy bound state
which exhibits non-Abelian statistics at each end emerges, which suggests that
a new topological invariant is needed to fully classify all phases. In a
comparatively large range of parameters, we find that spin-orbit coupling
induces completely flat band with nontrivial topology. For the case with
non-uniform dimerizaton, we find that spin-orbit coupling changes the
symmetrical structure of topological excitations known as solitons and
antisolitons and when spin-orbit coupling is strong enough to induce a
topological phase transition, the whole system is topologically nontrivial but
with the disappearance of solitons and antisolitons, consequently, the system
is a real topological insulator with well-protected end states.Comment: 5 pages, 2 figure
Condensate Fraction and Pair Coherence Lengths of Two-Dimension Fermi Gases with Spin-Orbit Coupling
The effects of Rashba spin-orbit coupling on BCS-BEC crossover, the
condensate fraction and pair coherence lengths for a two-component attractive
Fermi gas in two dimension are studied. The results at indicate that (1)
when the strength of SOC is beyond a critical value, BCS-BEC crossover does not
happen in a conventional sense; (2) SOC enhances the condensate fraction, but
suppresses pair coherence lengths
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