arXiv subjects

Peiyu Qin

Publications and source records attributed to Peiyu Qin.

4 recordsLinked to original sources

arXiv2026

Coexisting Charge Density Wave and Superconducting Order in Quantizing Magnetic Fields

Charge density wave (CDW) and superconductivity are both common in strongly interacting electron systems. While CDW order is ubiquitous in both quantum Hall systems and unconventional superconductors, superconductivity is generally suppressed by the strong magnetic fields required for Landau quantization. Here we investigate the intertwined CDW and superconducting phases of rhombohedral hexalayer graphene (R6G) in a large displacement field, which generates tunable flat band edges, and a strong magnetic field, which generates a manifold of nearly degenerate Landau levels. We find a series of integer quantum Hall effects with Hall conductance quantum numbers that deviate from nearby integer filling factors, an observation that can be explained only by CDW order that mixes many Landau levels. We also find a nearby superconducting phase stabilized by perpendicular magnetic fields and persists deep within the quantum Hall regime. This intertwinement provides new insight into superconductivity in R6G at zero magnetic field.

cond-mat.mes-hall↗

arXiv2026

Stripe Order in the Metallic and Superconducting Phases of Rhombohedral Hexalayer Graphene

In strongly correlated electronic systems, Coulomb interactions frequently give rise to emergent electronic orders that spontaneously break rotational symmetry. Understanding how such symmetry breaking intertwines with other collective phenomena-such as unconventional superconductivity-and how it shapes experimental observables, particularly transport responses, remains a central challenge in modern condensed-matter physics. Here we report experimental signatures of charge stripe order, with a transport anisotropy rivaling that of quantum Hall stripe phases, coexisting with superconductivity and magnetism in rhombohedral hexalayer graphene. Strikingly, the low-temperature superconducting state not only inherits strong anisotropy but also exhibits a wide range of hysteretic transitions arising from the tunability of the underlying stripe order. Together, these findings reveal a previously unrecognized coexistence between superconductivity and charge stripe, shedding new light on the role of rotational symmetry breaking in shaping unconventional superconductivity in rhombohedral graphene.

cond-mat.mes-hall↗

arXiv2025

Evidence of Momentum Space Condensation in Rhombohedral Hexalayer Graphene

Spontaneous symmetry breaking provides a powerful window into the nature of underlying electronic orders. In strongly correlated systems, multiple symmetry-breaking orders can arise simultaneously. and their interplay generates an intricate landscape of quantum phases that has remained a central focus of condensed-matter research. In this work, we report a previously unidentified electronic phase in rhombohedral hexalayer graphene, distinguished by the simultaneous breaking of rotational, time-reversal, and inversion symmetries. Broken rotational symmetry is evidenced through anisotropic transport in angle-resolved measurements, while the onset of both the anomalous Hall effect and the nonlinear Hall effect signals the breaking of time-reversal and inversion symmetries. These combined signatures reveal an emergent order consistent with momentum-space condensation, a theoretically anticipated phenomenon realized here experimentally for the first time. This mechanism establishes a natural framework for understanding a broader class of correlated phases known to emerge from the flat bands of two-dimensional materials.

cond-mat.mes-hall↗

arXiv2025

A Hierarchy of Superconductivity and Topological Charge Density Wave States in Rhombohedral Graphene

Superconductivity and the quantum Hall effect are conventionally regarded as mutually exclusive: superconductivity is suppressed by magnetic fields, whereas the quantum Hall effect relies on them. Here we report a striking exception, where an unconventional superconducting phase is stabilized by an out-of-plane magnetic field and coexists with a re-entrant integer quantum Hall (RIQH) effect in moiré-less rhombohedral hexalayer graphene. The re-entrant quantum Hall state, arising from a bubble-like charge density wave (CDW), provides a natural backdrop for the emergence of superconductivity. Angle-resolved transport reveals that the field-stabilized superconducting phase occupies the same density--displacement-field regime as a stripe-ordered phase at zero field, yet only develops once the stripe is replaced by a bubble-like CDW at finite field. These findings demonstrate a decisive role of CDW order in stabilizing superconductivity in rhombohedral graphene, establishing a new paradigm for the interplay between superconductivity and quantum Hall physics.

cond-mat.mes-hall↗