Who
Tyrel McQueen (JHU)
Abstract
The superconducting diode effect (SDE) [0] occurs in superconducting materials in which both spin and inversion symmetry are broken and leads to an asymmetry of charge transport -- supercurrent in one direction, and dissipative current in the other. Most experimental realizations of the SDE break inversion symmetry with structural elements, and then rely on an external applied magnetic field to break time reversal symmetry. Recent experimental observations of a zero-field diode effect in a planar josephson junction heterostructure of superconducting NbSe2 and insulating Nb3Br8 [1] suggest there may be more to the story, as Nb3Br8 is not known to break time reversal symmetry, leading to multiple alternative theories for the observed behavior, which has recently been replicated in junctions using Nb3Cl8 as the tunnel barrier. One possibility is that is arises by a mechanism similar to the known, 20-year-old, chirality-induced spin selectivity (CISS) effect -- an effect where a structurally chiral material does not (statically) break time-reversal symmetry, but none-the-less shows spin selective transport due to an effective magnetic field that depends on the handedness. To test this hypothesis, I will present electrical transport properties of right-handed/left-handed and right-handed/right-handed josephon-junction devices fabricated from single crystals of the structurally chiral superconductor Mo3Al2C, and show evidence for a zero-field diode effect in right-handed/left-handed devices but not right-handed/right-handed devices [2].
0. https://www.youtube.com/watch?v=2qieThb_fow
1. https://doi.org/10.1038/s41586-022-04504-8
2. https://arxiv.org/abs/2508.11629
0. https://www.youtube.com/watch?v=2qieThb_fow
1. https://doi.org/10.1038/s41586-022-04504-8
2. https://arxiv.org/abs/2508.11629