Reconfigurable chiral superconductivity
Surajit Dutta, Nadav Auerbach, Tonghang Han, Yaozhang Zhou, Gal Shavit, Niladri-Sekhar Kander, Yuri Myasoedov, Martin E. Huber
Abstract
Rhombohedral multilayer graphene at high displacement fields hosts superconductivity emerging from a spin valley polarized quarter metal, with transport signatures suggestive of time reversal symmetry (TRS) breaking and chiral superconductivity (CSC). These observations have motivated proposals of topological superconductivity and non-Abelian quasiparticles, yet direct magnetic evidence and microscopic insight into the superconducting state remain lacking, limiting understanding of this unique state. Here we use nanoscale SQUID on tip magnetometry to image isospin-polarized domains in rhombohedral pentalayer graphene and establish CSC via spatially resolved thermodynamic detection of TRS breaking. We find that the density at which domain walls proliferate at elevated temperatures coincides with the onset of CSC, indicating an underlying transition in the parent state that both induces superconductivity and reduces domain wall energy. We further show that the chiral domain structure in the superconducting phase is inherited from the isospin-polarized parent state. Strikingly, the CSC phase exhibits multiple transport regimes governed by configurations of chiral domains separated by highly resistive domain walls. We demonstrate deterministic, ultra low current control of these domains, enabling reversible switching between states of opposite chirality a defining CSC property absent in other superconductors. These results establish rhombohedral graphene as a unique platform for reconfigurable CSC and ultra low power electronic functionality based on controllable isospin textures.
AI Impact Assessments
(1 model)Scientific Impact Assessment: "Reconfigurable Chiral Superconductivity"
1. Core Contribution
This paper provides the first direct, spatially resolved thermodynamic evidence of time-reversal symmetry (TRS) breaking in a superconducting state of rhombohedral pentalayer graphene (R5G), establishing it as a chiral superconductor (CSC). Using nanoscale SQUID-on-tip (SOT) magnetometry, the authors image isospin-polarized domains with opposite out-of-plane magnetization deep within the superconducting phase, demonstrating that two degenerate chiral ground states coexist and can be switched between. Three key advances stand out: (i) direct magnetic imaging confirming macroscopic orbital TRS breaking in the superconducting state—something long sought in candidate chiral superconductors like Sr₂RuO₄ but never achieved; (ii) the demonstration that chiral domain structure is inherited from the parent quarter-metal (1/4M) isospin-polarized state; and (iii) deterministic, ultra-low-current (~1.7 nA) switching between opposite-chirality superconducting domains, establishing "reconfigurable" CSC as a new concept.
2. Methodological Rigor
The experimental approach is exceptionally thorough and well-designed. The combination of SOT magnetometry with simultaneous transport measurements provides complementary local and global probes. Key methodological strengths include:
A potential limitation is the non-standard contact geometry (all contacts on one edge), which complicates transport interpretation. However, the authors address this transparently with COMSOL modeling. The paper does not fully resolve whether the superconducting order parameter itself is intrinsically chiral or merely inherits chirality from the parent state—a distinction the authors explicitly acknowledge.
3. Potential Impact
Fundamental physics: This work addresses one of the most important open questions in condensed matter physics—the existence and nature of chiral superconductivity. The long and controversial history of Sr₂RuO₄ demonstrates how difficult it has been to establish CSC in any material. This paper provides the most compelling evidence to date for macroscopic TRS breaking in a superconductor via direct magnetic imaging, which is a thermodynamic probe rather than an indirect transport signature.
Topological quantum computing: Chiral superconductors are predicted to host non-Abelian quasiparticles, making this result directly relevant to proposals for topological quantum computation. The reconfigurability demonstrated here adds a new dimension—the ability to electrically control the topological state.
Isospintronics: The concept of ultra-low-current control of isospin domain walls, with switching currents ~6 orders of magnitude below conventional spintronics, opens a genuinely new paradigm. The momentum-transfer mechanism (rather than spin-transfer torque) identified here represents a qualitatively different regime of domain wall dynamics.
Broader 2D materials community: The insights into domain wall energetics, the connection between DW proliferation and superconducting onset, and the proposal of a hidden symmetry-breaking transition will stimulate extensive theoretical and experimental follow-up across the rhombohedral graphene and moiré materials communities.
4. Timeliness & Relevance
This paper arrives at a critical juncture. Following the discovery of superconductivity in rhombohedral graphene (2021-2024) and recent transport signatures suggestive of chirality (Han et al., Nature 2025), the field has been urgently seeking direct magnetic confirmation. Dozens of theoretical proposals for topological superconductivity in RMG have been published, but without direct experimental validation. This work fills precisely that gap, providing the thermodynamic evidence needed to validate or constrain these theories. The timing is also significant given the explosion of interest in fractional quantum anomalous Hall states in the same material platform.
5. Strengths & Limitations
Key Strengths:
Notable Limitations:
Additional Observations:
The Landau free-energy framework for understanding DW line tension reduction via a secondary order parameter (Extended Data Fig. 11) is elegant and provides a testable theoretical prediction. The observation that DW pinning increases below T_c, with quantitative consistency from BCS condensation energy estimates, strengthens the case for intimate coupling between superconductivity and domain structure.
This paper represents a major experimental breakthrough that will likely define the direction of research on chiral superconductivity and correlated states in rhombohedral graphene for years to come.
Generated May 30, 2026
Comparison History (120)
Paper 2 offers breakthrough experimental evidence of chiral superconductivity (CSC), a highly sought-after state for topological quantum computing. Unlike Paper 1, which presents a strong but purely theoretical proposal for Floquet engineering, Paper 2 provides direct nanoscale magnetic imaging of time-reversal symmetry breaking in graphene. Furthermore, demonstrating deterministic, ultra-low current control to reversibly switch chirality is an unprecedented experimental achievement with immediate, high-impact applications in low-power electronics and quantum devices. Its combination of fundamental microscopic discovery and practical device reconfigurability gives it a wider and more immediate scientific impact.
Paper 2 demonstrates unprecedented deterministic control over chiral superconducting domains, a property absent in other superconductors. While Paper 1 provides a crucial framework for understanding graphene's band structure, Paper 2 leverages SQUID magnetometry to directly visualize and reconfigure time-reversal symmetry breaking. This breakthrough capability to reversibly switch chirality states at ultra-low currents opens direct pathways for novel ultra-low power electronics and advances the quest for topological quantum computing. Paper 2's combination of a fundamental physics breakthrough with immediate functional applications gives it a higher potential impact.
Paper 1 provides direct experimental evidence for chiral superconductivity in rhombohedral graphene, resolving a major open question with novel SQUID-on-tip imaging, and demonstrates reversible chirality switching with practical low-power device implications and connections to topological superconductivity. Its combination of methodological innovation, timeliness in a hot field, and potential technological applications gives broad impact. Paper 2 offers an elegant theoretical framework linking STM to band topology with useful applications, but is more incremental and specialized, with narrower immediate real-world consequences compared to the transformative experimental breakthrough in Paper 1.
While Paper 1 offers an innovative materials approach to neuromorphic computing, Paper 2 provides groundbreaking direct thermodynamic evidence of chiral superconductivity and time-reversal symmetry breaking—a major holy grail in condensed matter physics. Furthermore, demonstrating deterministic control and reversible switching of chiral domains introduces fundamentally new physics absent in other known superconductors. The potential downstream impact on topological quantum computing, specifically regarding non-Abelian quasiparticles, gives Paper 2 a significantly higher ceiling for both fundamental scientific paradigm-shifting and long-term technological applications.
Paper 1 provides direct thermodynamic evidence for chiral superconductivity and demonstrates reversible, ultra-low-power switching of chirality domains—a novel, technologically relevant capability tied to hot topics like topological superconductivity and non-Abelian physics. Its innovative SQUID-on-tip imaging and device functionality suggest broad impact. Paper 2 elegantly resolves a longstanding question about interaction effects on quantum Hall criticality (z=2 verification), showing strong rigor, but addresses a more specialized, foundational problem with narrower downstream applications compared to Paper 1's platform for reconfigurable quantum electronics.
Paper 1 reports the groundbreaking discovery and deterministic control of reconfigurable chiral superconductivity in rhombohedral graphene. This represents a major leap in fundamental condensed matter physics, directly enabling potential breakthroughs in topological quantum computing and ultra-low power electronics. While Paper 2 offers a highly valuable methodological advancement in nanoscale magnetic imaging for spintronics, Paper 1's realization and manipulation of a unique, long-sought quantum state of matter provides higher potential for transformative impact and wider relevance in next-generation quantum technologies.
Paper 1 addresses chiral superconductivity in rhombohedral graphene, a highly active frontier tied to topological superconductivity and non-Abelian physics. Using novel SQUID-on-tip magnetometry, it provides direct thermodynamic evidence of TRS breaking and demonstrates reversible chirality switching—a defining CSC property with implications for topological quantum computing and low-power electronics. This tackles a fundamental open question with broad theoretical and applied significance. Paper 2 offers solid, novel work on noncollinear moiré XY magnets with spintronics potential, but its impact is more incremental within the twisted-magnet subfield compared to Paper 1's transformative superconductivity findings.
Paper 1 offers a groundbreaking experimental realization and control of chiral superconductivity in rhombohedral graphene. By providing direct magnetic evidence of time-reversal symmetry breaking and demonstrating ultra-low power reversible switching of chiral domains, it resolves a major open question in condensed matter physics. This bridges fundamental topological physics with tangible next-generation quantum computing and low-power electronic applications. While Paper 2 presents an elegant theoretical framework for quasicrystals, Paper 1's combination of cutting-edge experimental rigor, profound novelty, and immediate technological relevance gives it significantly higher potential for broad scientific impact.
Paper 1 provides direct experimental evidence of chiral superconductivity via novel nanoscale SQUID imaging, demonstrating deterministic switching between opposite chirality states—a landmark result addressing timely questions about topological superconductivity and non-Abelian physics in rhombohedral graphene. It combines methodological innovation with immediate device applications (reconfigurable ultra-low-power electronics). Paper 2 offers valuable theoretical insights into decoherence in topological insulators with new scaling laws, but is more incremental and awaits experimental validation. Paper 1's direct evidence resolving major open questions and its broad relevance to quantum materials give it higher impact.
Paper 2 likely has higher impact due to its combination of strong novelty (direct thermodynamic imaging evidence of TRS breaking and reconfigurable chiral superconductivity), major real-world potential (ultra-low-power, switchable chirality states relevant to topological/quantum devices), and broad, timely relevance across condensed matter, topological physics, and quantum engineering. Its use of nanoscale SQUID magnetometry provides rigorous microscopic insight beyond transport-only signatures. Paper 1 is important for driven-dissipative exciton condensates, but its applications and cross-field reach are comparatively narrower.