Abstract
Normal superconductors with Rashba spin-orbit coupling have been explored as candidate systems of topological superconductors. Here we present a comparative theoretical study of the effects of different types of disorder on the topological phases of two-dimensional Rashba spin-orbit coupled superconductors. First, we show that a topologically trivial superconductor can be driven into a chiral topological superconductor upon diluted doping of isolated magnetic disorder, which close and reopen the quasiparticle gap of the paired electrons in a nontrivial manner. Secondly, the superconducting nature of a topological superconductor is found to be robust against Anderson disorder, but the topological nature is not, converting the system into a topologically trivial state even in the weak scattering limit. These topological phase transitions are distinctly characterized by variations in the topological invariant. We discuss the central findings in connection with existing experiments, and provide new schemes towards eventual realization of topological superconductors.
Highlights
We carry out a comparative study using complementary theoretical approaches to explore the potential existence of topological phase transitions in 2D Rashba spin-orbit coupled superconductors by proper introduction of different types of disorder
We use the self-consistent Born approximation (SCBA) to investigate the disorder renormalized density of states (DOS) of the systems, and show that a topologically trivial superconductor can be driven into a chiral Topological superconductors (TSCs) upon diluted doping of isolated magnetic disorder
When V0 crosses a critical value Vc, the quasiparticle gap reopens, and the system enters a trivial superconducting state. These findings suggest that, as far as Anderson disorder is concerned, a cleaner superconducting system is better for the realization of TSC
Summary
Framework for further studying the disorder-induced effects on the topological phases of such spin-orbited coupled superconducting systems. A critical concentration nc for such a topological quantum phase transition is clearly identifiable In this regime containing sufficient magnetic impurities (with nim > 1.2% in the present study), the system is a gapless superconductor with non-vanishing superconducting order parameter[16]. When V0 crosses a critical value Vc, the quasiparticle gap reopens, and the system enters a trivial superconducting state These findings suggest that, as far as Anderson disorder is concerned, a cleaner superconducting system is better for the realization of TSC. We adopt an alternative and more general formula for evaluating the topological invariant, which relies on the full Green’s function of the interacting system as[39,40,41]:
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