Driving the field-free Josephson diode effect using Kagome Mott insulator barriers
Abstract
Josephson junctions (JJs), devices consisting of two superconductors separated by a barrier, are of great technological importance, being a cornerstone of quantum information processing. Classical understanding of superconductor-insulator-superconductor JJs is that conventional insulator's properties, other than magnetism, do not significantly influence the junction's behavior. However, recent work on quantum material (QM) JJs - using Mott insulator Nb3Br8 - resulted in magnetic field-free non-reciprocal superconductivity, termed the Josephson diode effect (JDE), implying the QM's intrinsic properties can modulate superconductivity in non-trivial ways. To date, the underlying mechanism and dependence of the JDE on correlation strength (U/t) has not been elucidated. Here we fabricate QMJJs using correlated Kagome insulators with varying U/t, Nb3X8 (X=Cl, Br, I), observing a decreasing trend of the field-free JDE with Nb3Cl8 reaching ~48% efficiency, Nb3Br8 ~6%, and Nb3I8 having no discernible JDE, matching the trend of decreasing U/t from Cl to I and suggesting correlation in insulators drives the field-free JDE.
Keywords
Cite
@article{arxiv.2512.17099,
title = {Driving the field-free Josephson diode effect using Kagome Mott insulator barriers},
author = {Michiel P. Dubbelman and Heng Wu and Joost Aretz and Yaojia Wang and Chris M. Pasco and Yuzhou Zhao and Trent M. Kyrk and Jihui Yang and Xiaodong Xu and Tyrel M. McQueen and Malte Roesner and Mazhar N. Ali},
journal= {arXiv preprint arXiv:2512.17099},
year = {2025}
}
Comments
7 pages main text (15 pages in total), 4 main text figures (9 figures total)