Superconducting quantum spin-Hall systems with giant orbital g-factors

Abstract

Topological aspects of superconductivity in quantum spin-Hall systems (QSHSs) such as thin layers of three-dimensional topological insulators (3D Tis) or two-dimensional Tis are in the focus of current research. We examine hybrid QSHS/superconductor structures in an external magnetic field and predict a gapless superconducting state with protected edge modes. It originates entirely from the orbital magnetic-field effect caused by the locking of the electron spin to the momentum of the superconducting condensate flow. We show that such spin-momentum locking can generate a giant orbital g-factor of order of several hundreds, allowing one to achieve significant spin polarization in the QSHS in the fields well below the critical field of the superconducting material. We propose a three-terminal setup in which the spin-polarized edge superconductivity can be probed by Andreev reflection, leading to unusual transport characteristics: a non-monotonic excess current and a zero-bias conductance splitting in the absence of the Zeeman interaction.

14 pages, 6 figures

References in corpus (7)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Dissipationless Quantum Spin Current at Room Temperature
• Edge-mode Superconductivity in a Two Dimensional Topological Insulator
• Spin-helical transport in normal and superconducting topological insulators
• Induced superconductivity in the three-dimensional topological insulator HgTe
• Andreev magnetotransport in low-dimensional proximity structures: Spin-dependent conductance enhancement

Cited by in corpus (5)

• Discovery of segmented Fermi surface induced by Cooper pair momentum
• Superconducting proximity effect in three-dimensional topological insulators in the presence of a magnetic field
• Zeeman-Induced Gapless Superconductivity with Partial Fermi Surface
• Meissner effect induced Majorana zero modes at small magnetic field
• Giant spin splitting and $0-\pi$ Josephson transitions from the Edelstein effect in quantum spin-Hall insulators