Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Focus Session: Superconductivity in 2d-Materials and their Heterostructures
TT 10.6: Talk
Tuesday, September 6, 2022, 12:15–12:30, H3
Josephson diode effect in a Dirac semimetal NiTe2 — Banabir Pal1, •Anirban Chakraborty1, Pranava K. Sivakumar1, Margarita Davydova2, Ajesh K. Gopi1, Avanindra K. Pandeya1, Jonas A. Krieger1, Yang Zhang2, Mihir Date1, Sailong Ju3, Noah Yuan2, Niels B.M. Schröter1, Liang Fu2, and Stuart S.P. Parkin1 — 1Max Planck Institute of Microstructure Physics, Halle (Saale) 06120, Germany — 2Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA — 3Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
In the presence of an external magnetic field, Cooper pairs in a noncentrosymmetric superconductor can acquire a finite momentum that may give rise to a plethora of intriguing phenomena such as topological superconductivity and Majorana bound states. Recently theory predicts that such finite-momentum pairing can produce a nonreciprocal critical current leading to a unidirectional dissipationless supercurrent, dubbed the superconducting diode effect. Here we demonstrate a large asymmetry in critical currents depending on the polarity of the current bias in a Josephson junction fabricated using a type – II Dirac semimetal NiTe2 under a small in-plane magnetic field. The asymmetry depends on the direction and magnitude of the field and is maximized when this field is perpendicular to the supercurrent flow. Our experimental evidence and theoretical analysis show that the observed ‘Josephson diode effect’ is enabled by finite momentum Cooper pairing in the spin-helical topological surface states, in an otherwise centrosymmetric system. The finite Cooper pair momentum in the system is further established, and its value determined, by the evolution of the Fraunhofer pattern with the magnetic field.