Evidence for an Anomalous Current-Phase Relation in Topological Insulator Josephson Junctions
Josephson junctions with topological insulator weak links can host low-energy Andreev-bound states giving rise to a current-phase relation that deviates from sinusoidal behaviour. Of particular interest are zero-energy Majorana-bound states that form at a phase difference of π. Here we report on interferometry studies of Josephson junctions and superconducting quantum interference devices (SQUIDs) incorporating topological insulator weak links. We find that the nodes in single-junction diffraction patterns and SQUID oscillations are lifted and independent of chemical potential. At high temperatures, the SQUID oscillations revert to conventional behaviour, ruling out asymmetry. The node-lifting of the SQUID oscillations is consistent with low-energy Andreev-bound states exhibiting a nonsinusoidal current-phase relation, co-existing with states possessing a conventional sinusoidal current-phase relation. However, the finite nodal currents in the single-junction diffraction pattern suggest an anomalous contribution to the supercurrent possibly carried by Majorana-bound states, although we also consider the possibility of inhomogeneity.
C. Kurter et al., "Evidence for an Anomalous Current-Phase Relation in Topological Insulator Josephson Junctions," Nature Communications, vol. 6, Nature Publishing Group, Jun 2015.
The definitive version is available at https://doi.org/10.1038/ncomms8130
Keywords and Phrases
Diffraction; Magnetic Field; Oscillation; Quantum Mechanics; Superconductivity; Topology; Electrical Equipment; High Temperature; Interferometry; Josephson Junction; Low Temperature; Magnetic Field; Oscillation; Superconducting Quantum Interference Device; Superconductor; Cephalopoda; Majorana
International Standard Serial Number (ISSN)
Article - Journal
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01 Jun 2015