27,179 research outputs found
Odd-parity topological superconductor with nematic order: Application to CuxBi2Se3
CuxBi2Se3 was recently proposed as a promising candidate for
time-reversal-invariant topological superconductors[1]. In this work, we argue
that the unusual anisotropy of the Knight shift observed by Zheng[2], taken
together with specific heat measurements, provides strong support for an
unconventional odd-parity pairing in the two-dimensional E_u representation of
the D3d crystal point group[1], which spontaneously breaks the three-fold
rotational symmetry of the crystal, leading to a subsidiary nematic order. We
predict that the spin-orbit interaction associated with hexagonal warping plays
a crucial role in pinning the two-component order parameter and makes the
superconducting state fully-gapped, leading to a topological superconductor.
Experimental signatures of the E_u pairing related to the nematic order are
discussed.Comment: accepted by Phys. Rev. B Rapid Communicatio
Parity-breaking phases of spin-orbit-coupled metals with gyrotropic, ferroelectric and multipolar orders
We study Fermi liquid instabilities in spin-orbit-coupled metals with
inversion symmetry. By introducing a canonical basis for the doubly degenerate
Bloch bands in momentum space, we derive the general form of interaction
functions. A variety of time-reversal-invariant, parity-breaking phases is
found, whose Fermi surface is spontaneously deformed and spin-split. In terms
of symmetry, these phases possess gyrotropic, ferroelectric and multipolar
orders. The ferroelectric and multipolar phases are accompanied by structural
distortions, from which the electronic orders can be identified. The gyrotropic
phase exhibits a unique nonlinear optical property. Based on recent
experiments, we identify several interesting quantum materials including
pyrochlore oxides, which show evidence of these parity breaking orders.Comment: 5 page
Topological Crystalline Insulators
The recent discovery of topological insulators has revived interest in the
topological properties of insulating band structures. In this work, we extend
the topological classification of insulating band structures to include certain
point group symmetry of crystals. We find a class of three-dimensional
"topological crystalline insulators" which have metallic surface states on
certain high symmetry crystal surfaces. These topological crystalline
insulators can be viewed as the counterpart of topological insulators in
materials without spin-orbit coupling. Their surface states have quadratic band
degeneracy instead of linear Dirac dispersion. Their band structures are
characterized by new Z2 invariants. We hope this work will enlarge the family
of topological phases in band insulators and stimulate the search for them in
real materials.Comment: published version, added an appendix on the stability of surface
state
Majorana Superconducting Qubit
We propose a platform for universal quantum computation that uses
conventional -wave superconducting leads to address a topological qubit
stored in spatially separated Majorana bound states in a multi-terminal
topological superconductor island. Both the manipulation and read-out of this
"Majorana superconducting qubit" are realized by tunnel couplings between
Majorana bound states and the superconducting leads. The ability of turning on
and off tunnel couplings on-demand by local gates enables individual qubit
addressability while avoiding cross-talk errors. By combining the scalability
of superconducting qubit and the robustness of topological qubits, the Majorana
superconducting qubit may provide a promising and realistic route towards
quantum computation
Topological Crystalline Insulators and Topological Superconductors: From Concepts to Materials
In this review, we discuss recent progress in the explorations of topological
materials beyond topological insulators; specifically, we focus on topological
crystalline insulators and bulk topological superconductors. The basic
concepts, model Hamiltonians, and novel electronic properties of these new
topological materials are explained. The key role of symmetries that underlie
their topological properties is elucidated. Key issues in their materials
realizations are also discussed.Comment: 27 pages, 5 figures, 150 references; invited review article to be
published in Annual Review of Condensed Matter Physics, Volume
- …