Many-body interference in kagome crystals
Article meta
Article Date: 29 October 2025
Article URL: https://www.nature.com/articles/s41586-025-09659-8
Main image: figure 1
Summary
This Nature paper reports the discovery of macroscopic, field-periodic magnetoresistance oscillations (h/e periodicity per kagome layer) in micron-scale pillars of the kagome metal CsV3Sb5. The oscillation period scales inversely with device width and matches the flux quantum threaded between adjacent kagome layers, indicating sensitivity to in-plane confinement over micrometre distances. The effect appears below an intermediate temperature scale T’ ~ 30 K, can be switched discontinuously by rotating the in-plane magnetic field (with switching angles set by sample geometry), is strongly suppressed by out-of-plane tilts and by strain, and persists on length scales far exceeding both transport and quantum mean free paths. The authors argue these signatures point to a long-range, coherent many-body electronic state (distinct from bulk superconductivity) that contributes coherently to out-of-plane charge transport.
Key Points
- Field-periodic oscillations in interlayer magnetoconductance with period ΔB·w·c ≈ h/e (flux quantum per interlayer spacing) are observed in CsV3Sb5 micro-pillars.
- The oscillation period scales inversely with device width (1–3 μm) and uses the nearest-neighbour interlayer spacing as the relevant length scale.
- Oscillations persist over micrometre distances even though the transport and quantum mean free paths are ≲560 nm and ≲200 nm respectively, ruling out simple single-particle ballistic explanations.
- When the in-plane field is rotated, the oscillation frequency switches discontinuously at angles determined by sample geometry (rectangles: 90°; parallelogram: 60°/120°), implying non-local coherent coupling between surfaces.
- The effect appears below T’ ≈ 30 K, tracks other probes of the enigmatic intermediate state (STM, μSR, NMR, anomalous Nernst), and is strongly suppressed by strain and small out-of-plane field components.
- Authors interpret results as evidence for a macroscopically coherent many-body electronic state (candidates: orbital loop currents, excitonic or coupled charge–spin correlations) that is dissipative yet phase-stiff and contributes to transport in a manner reminiscent of layered superconductors.
- Implications include new constraints on microscopic models of CsV3Sb5 and potential routes to geometry-driven coherent devices that operate without superconductivity.
Content summary
The team fabricated suspended, strain-minimised micro-pillars from high-quality CsV3Sb5 crystals using focused-ion-beam machining. With current along the c axis and magnetic field applied in plane, they measured interlayer magnetoconductance and found pronounced oscillations periodic in B. The period obeys ΔB = Φ0/(w·c) (Φ0 = h/e), linking the signal to flux threaded between adjacent kagome layers. The phenomenon is reproducible across devices and persists to temperatures up to ~25 K, collapsing toward the noise floor near T’≈30 K.
Key experimental diagnostics exclude single-particle ballistic scenarios: the effect survives in samples whose dimensions exceed measured transport mean free paths by up to an order of magnitude, and Dingle analysis yields short quantum mean free paths. The oscillation amplitude is extinguished by small tilts out of plane (θ ≈ 5°) and strongly reduced by applied tensile strain — both behaviours incompatible with conventional flux-projection single-particle mechanisms but consistent with a phase-coherent many-body wavefunction that is sensitive to vortex-like excitations or phase singularities.
Angular studies show abrupt switching of the oscillation frequency as the in-plane field is rotated; switching angles follow the sample cross-section internal angles, indicating that geometry, surface termination and crystal orientation create a non-trivial energy landscape for the coherent state. Temperature dependence and comparisons with prior probes suggest the coherent state condenses out of an incoherent, fluctuating parent that links back to charge-order physics.
Context and relevance
CsV3Sb5 is a topical kagome metal with intertwined charge order, possible time-reversal breaking and low-T superconductivity. This work reveals a new, coherent transport channel in the normal state that shares coherence features with superconductors but remains dissipative. It directly bears on debates over the intermediate-temperature phase (T’~30 K) in AV3Sb5 materials, constrains microscopic scenarios (loop currents, excitons, vestigial orders), and highlights how geometry and frustration can be used to engineer coherence in correlated materials. For researchers working on correlated electrons, topological metals or device concepts exploiting quantum interference, these results open a fresh design axis: use geometry and confinement to stabilise coherent many-body responses even outside the superconducting state.
Why should I read this?
Because it’s one of those neat papers that actually hands you a clear, reproducible experimental fingerprint of something genuinely weird: coherent, geometry-tuned transport over micrometre distances in a non-superconducting normal state. If you care about strange-metal physics, kagome lattices, or new ways to get quantum-coherent behaviour without relying on superconductors, this saves you the legwork — the authors did the delicate fabrication, angle sweeps and mean-free-path checks so you don’t have to.