Zero-field superconducting diode effect in small-twist-angle trilayer graphene

The critical current of a superconductor can be different for opposite directions of current flow when both time-reversal and inversion symmetry are broken. Such non-reciprocal behaviour creates a superconducting diode and has recently been experimentally demonstrated by breaking these symmetries wi...

Full description

Saved in:
Bibliographic Details
Published in:Nature physics 2022-10, Vol.18 (10), p.1221-1227
Main Authors: Lin, Jiang-Xiazi, Siriviboon, Phum, Scammell, Harley D., Liu, Song, Rhodes, Daniel, Watanabe, K., Taniguchi, T., Hone, James, Scheurer, Mathias S., Li, J.I.A.
Format: Article
Language:English
Subjects:
639/766/119/1003
639/766/119/995
Atomic
Broken symmetry
Carrier density
Classical and Continuum Physics
Complex Systems
Condensed Matter Physics
Critical current (superconductivity)
Fermi surfaces
Graphene
Magnetic fields
Magnetism
Mathematical and Computational Physics
Molecular
Momentum
Optical and Plasma Physics
Physics
Physics and Astronomy
Reciprocation
Superconductivity
Symmetry
Theoretical
Tunnel construction
Tunnel junctions
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The critical current of a superconductor can be different for opposite directions of current flow when both time-reversal and inversion symmetry are broken. Such non-reciprocal behaviour creates a superconducting diode and has recently been experimentally demonstrated by breaking these symmetries with an applied magnetic field or by the construction of a magnetic tunnel junction. Here we report an intrinsic superconducting diode effect that is present at zero external magnetic field in mirror-symmetric twisted trilayer graphene. Such non-reciprocal behaviour, with sign that can be reversed through training with an out-of-plane magnetic field, provides direct evidence of the microscopic coexistence between superconductivity and time-reversal symmetry breaking. In addition to the magnetic-field trainability, we show that the zero-field diode effect can be controlled by varying the carrier density or twist angle. A natural interpretation for the origin of the intrinsic diode effect is an imbalance in the valley occupation of the underlying Fermi surface, which probably leads to finite-momentum Cooper pairing and nematicity in the superconducting phase. A superconducting diode effect is observed at zero magnetic field in twisted trilayer graphene. This suggests that time-reversal symmetry is intrinsically broken and leads to pairing between electrons with non-zero centre-of-mass momentum.
ISSN:1745-2473
1745-2481
DOI:10.1038/s41567-022-01700-1