Spin-Orbit induced phase-shift in Bi2Se3 Josephson junctions

The transmission of Cooper pairs between two weakly coupled superconductors produces a superfluid current and a phase difference ; the celebrated Josephson effect.
Because of time-reversal and parity symmetries, there is no Josephson current without a phase difference between the two superconductors. Reciprocally, when those two symmetries are broken, an anomalous supercurrent can exist in the absence of phase bias or, equivalently, an anomalous phase shift φ_0 can exist in the absence of a superfluid current.
We report on the observation of an anomalous phase shift φ_0 in hybrid Josephson junctions fabricated with the topological insulator Bi2Se3 submitted to an in-plane magnetic field. This anomalous phase shift φ_0 is observed directly through measurements of the current-phase relationship in a Josephson interferometer.
This result provides a direct measurement of the spin-orbit coupling strength and open new possibilities for phase-controlled Josephson devices made from materials with strong spin-orbit coupling.

Reference :
Assouline, A. et al. Spin-Orbit induced phase-shift in Bi2Se3 Josephson junctions. Nat. Commun. 10, 126 (2019).
Contact : herve.aubin (arobase) c2n.upsaclay.fr OR alexandre.assouline (arobase) cea.fr
Site Web : http://qtg.lpem.espci.fr

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