Magnetoelectrics in Disordered Topological Insulator Josephson Junctions

Abstract

We theoretically study the coupling of electric charge and spin polarization in an equilibrium and nonequilibrium electric transport across a two dimensional Josephson configuration comprised of disordered surface channels of a three dimensional topological insulator. In the equilibriun state of the system we predict the Edelstein effect, which is much more pronounced than its counterpart in conventional spin orbit coupled materials. Employing a quasiclassical Keldysh technique, we demonstrate that the ground state of system can be experimentally shifted into arbitrary macroscopic superconducting phase differences other than the standard `$0$' or `$\pi$', constituting a ${\varphi }_0$-junction, solely by modulating a quasiparticle flow injection into the junction. We propose a feasible experiment where the quasiparticles are injected into the topological insulator surface by means of a normal electrode and voltage gradient so that oppositely oriented stationary spin densities can be developed along the interfaces and allow for directly making use of the spin-momentum locking nature of Dirac fermions in the surface channels. The ${\varphi }_0$-state is proportional to the voltage difference applied between the injector electrode and superconducting terminals that calibrates the injection rate of particles and, therefore, the ${\varphi }_0$ shift.

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Cited by in corpus (7)

• Spontaneous supercurrent and $\varphi$0 phase shift parallel to magnetized topological insulator interfaces
• Generalized quasiclassical theory of the long-range proximity effect and spontaneous currents in superconducting heterostructures with strong ferromagnets
• Supercurrent generation by spin injection in an s-wave superconductor-Rashba metal bilayer
• Electrically controllable spin filtering based on superconducting helical states
• Electrically modulated SQUID with single Josephson junction coupled by a time-reversal breaking Weyl semimetal thin film
• ${\theta }_0$ thermal Josephson junction
• Spin-charge conversion in disordered two-dimensional electron gases lacking inversion symmetry