Tunable zero-energy Dirac and Luttinger nodes in a two-dimensional topological superconductor

Abstract

Cooper pairing in ultrathin films of topological insulators, induced intrinsically or by proximity effect, can produce an energetically favorable spin-triplet superconducting state. The spin-orbit coupling acts as an SU(2) gauge field and stimulates the formation of a spin-current vortex lattice in this superconducting state. Here we study the Bogoliubov quasiparticles in such a state and find that the quasiparticle spectrum consists of a number of Dirac nodes pinned to zero energy by the particle-hole symmetry. Some nodes are "accidental" and move through the first Brillouin zone along high-symmetry directions as the order parameter magnitude or the strength of the spin-orbit coupling are varied. At special parameter values, nodes forming neutral quadruplets merge and become gapped out, temporarily producing a quadratic band-touching spectrum. All these features are tunable by controlling the order parameter magnitude via a gate voltage in a heterostructure device. In addition to analyzing the spectrum at the mean-field level, we briefly discuss a few experimental signatures of this spectrum.

References in corpus (18)

• Classification of topological insulators and superconductors in three spatial dimensions
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• Topological Phases of Noncentrosymmetric Superconductors: Edge States, Majorana Fermions, and the Non-Abelian Statistics
• Topology of crystalline insulators and superconductors
• Correlated Topological Insulators with Mixed Valence
• Classification of reflection symmetry protected topological semimetals and nodal superconductors
• Topological spin-current in non-centrosymmetric superconductors
• Topological Mott insulator in three-dimensional systems with quadratic band touching
• Magnetic orders and topological phases from f-d exchange in pyrochlore iridates
• Topological Blount's theorem of odd-parity superconductors
• Nodal Structure of Superconductors with Time-Reversal Invariance and Z2 Topological Number
• Phase diagram of electronic systems with quadratic Fermi nodes in $2<d<4$: $2+\epsilon$ expansion, $4-\epsilon$ expansion, and functional renormalization group
• Anisotropy induces non-Fermi-liquid behavior and nematic magnetic order in three-dimensional Luttinger semimetals
• Symmetry protected line nodes in non-symmorphic magnetic space groups: Applications to UCoGe and UPd${}_2$Al${}_3$
• Electron interactions, spin-orbit coupling, intersite correlations in pyrochlore iridates
• First-principles study on cubic pyrochlore iridates Y2Ir2O7 and Pr2Ir2O7
• Two-dimensional heavy fermions on the strongly correlated boundaries of Kondo topological insulators
• Vortices and vortex states in Rashba spin-orbit-coupled condensates