Cavity-altered superconductivity.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41741741.
- Also identified by DOI 10.1038/s41586-025-10062-6 and PMC identifier 12935536.
- Licence recorded as CC BY-NC-ND.
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Abstract
Is it feasible to alter the ground-state properties of a material by engineering its electromagnetic environment? Inspired by theoretical predictions<sup>1-12</sup>, experimental realizations of such cavity-controlled properties without optical excitation are beginning to emerge<sup>13-19</sup>. Here we devised and implemented a new platform to realize cavity-altered materials. Single crystals of hyperbolic van der Waals (vdW) compounds provide a resonant electromagnetic environment with enhanced density of photonic states and prominent mode confinement<sup>20-24</sup>. We interfaced hexagonal boron nitride (hBN) with the molecular superconductor κ-(BEDT-TTF)<sub>2</sub>Cu[N(CN)<sub>2</sub>]Br (κ-ET). The frequencies of infrared hyperbolic modes (HMs) of hBN (refs. <sup>25,26</sup>) match the infrared-active carbon-carbon (C=C) stretching molecular resonance of κ-ET implicated in superconductivity<sup>27</sup>. Nano-optical data supported by first-principles molecular Langevin dynamics simulations confirm the presence of resonant coupling between the hBN hyperbolic cavity modes and the C=C stretching mode in κ-ET. Meissner-effect measurements using magnetic force microscopy (MFM) demonstrate a strong suppression of superfluid density near the hBN/κ-ET interface. Non-resonant control heterostructures, including RuCl<sub>3</sub>/κ-ET and hBN/Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x</sub> (BSCCO), do not show the pronounced superfluid suppression. These observations suggest that hBN/κ-ET realizes a cavity-altered superconducting ground state. Our work highlights the potential of dark cavities devoid of external photons for engineering electronic ground-state properties of complex quantum materials.