Speaker
Description
Chiral superconductivity is a long-sought quantum state that spontaneously breaks time-reversal symmetry and, in appropriate topological realizations, can host exotic excitations with potential applications in quantum information. Despite decades of theoretical and experimental effort, direct thermodynamic evidence for this elusive phase has remained absent. Rhombohedral multilayer graphene has recently emerged as a particularly intriguing platform, hosting superconductivity that develops from a spin–valley-polarized quarter-metal and exhibits transport signatures suggestive of time-reversal symmetry (TRS) breaking and chiral superconductivity (CSC) [1]. Using nanoscale SQUID-on-tip magnetometry [2], we directly image spontaneous TRS breaking and domains of opposite chirality in rhombohedral pentalayer graphene, thereby establishing CSC thermodynamically [3]. Remarkably, these chiral superconducting domains emerge from a symmetry-broken isospin-polarized parent state, revealing an intimate connection between symmetry breaking in the normal and superconducting phases. The carrier density at which domain walls proliferate at elevated temperatures coincides with the onset of CSC, pointing to an underlying transition in the parent state that both induces superconductivity and reduces the domain-wall energy. The CSC phase exhibits multiple transport regimes governed by configurations of chiral domains separated by highly resistive domain walls. We further demonstrate deterministic, reversible electrical control of these domains with ultra-low currents, enabling switching between superconducting states of opposite chirality. These findings establish rhombohedral graphene as a unique platform for exploring reconfigurable chiral and potentially topological superconductivity and for ultra-low-power electronic functionality based on controllable isospin textures.
[1] T. Han, Z. Lu, Z. Hadjri, L. Shi, Z. Wu, W. Xu, Y. Yao, A. A. Cotten, O. Sharifi Sedeh, H. Weldeyesus, J. Yang, J. Seo, S. Ye, M. Zhou, H. Liu, G. Shi, Z. Hua, K. Watanabe, T. Taniguchi, P. Xiong, D. M. Zumbühl, L. Fu, and L. Ju, Nature 643, 654 (2025).
[2] N. Auerbach, S. Dutta, M. Uzan, Y. Vituri, Y. Zhou, A.Y. Meltzer, S. Grover, T. Holder, P. Emanuel, M.E. Huber, Y. Myasoedov, K. Watanabe, T. Taniguchi, Y. Oreg, E. Berg, and E. Zeldov, Nat. Phys. 21, 1765 (2025).
[3] S. Dutta, N. Auerbach, T. Han, Y. Zhou, G. Shavit, N. S. Kander, Y. Myasoedov, M. E. Huber, K. Watanabe, T. Taniguchi, L. Ju, and E. Zeldov, arXiv:2605.13303.