Edge currents as a probe of the strongly spin-polarized topological noncentrosymmetric superconductors (original) (raw)
Recently the influence of antisymmetric spin-orbit coupling has been studied in novel topological superconductors such as half-Heuslers and artificial hetero-structures. We investigate the effect of Rashba and/or Dresselhaus spin-orbit couplings on the band structure and topological properties of a two-dimensional noncentrosymetric superconductor. For this goal, the topological helical edge modes are analyzed for different spin-orbit couplings as well as for several superconducting pairing symmetries. To explore the transport properties, we examine the response of the spin-polarized edge states to an exchange field in a superconductor-ferromagnet heterostructure. The broken chiral symmetry causes the uni-directional currents at opposite edges. I. INTRODUCTION Discovery of novel phases in the nodal systems has extended the classification of states of matter from the bulk gapped topological insulators to the gapless systems such as topological superconductors 1-5 and semimetals 6-10. The former are new quantum states with unconventional pairing symmetries exhibiting edge modes. These zero-energy gapless modes can host Majorana fermions, which obey non-Abelian statistics unlike bosons and fermions. These exotic edge modes are topologically protected against disorders and perturbations that gives them many promising applications 11-13. One of the most prominent platforms to realize the topological superconductivity is the class of noncentrosymmetric superconductors (NCSs) 14-26. These materials lack inversion symmetry and are characterized by strong antisymmetric spin-orbit coupling (SOC), which induces a non-trivial topology for the electronic band structure 27. This leads to the existence of helical Majorana modes, zero-energy flat-bands 15,24,28 and arc surface states 29,30. Recently attention has been attracted by the influence of SOC on structure of superconducting gap function and topological nature of superconductors, particularly in electronic and spintronic device design 13,31-37. The topological nature of NCSs and consequently the properties of the accompanied surface states can be controlled by SOC as well as the superconducting gap function 38,39. Moreover, SOC and relative amplitudes of singlet-and triplet-pairings in the superconducting gap can strongly affect the spin texture of the edge states in NCSs and eventually the transport properties at the surface 40,41. Thus, the symmetries of superconducting gap and SOC strength support the different types of topological surface states in noncentrosymmetric superconductors like LiPt 3 B 42
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