Remote magnon sensing detects the universal phase stiffness jump in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$
Year: 2026
Type: preprint
Abstract: Phase stiffness governs macroscopic quantum coherence in superfluids and superconductors, providing a sensitive probe of condensate depletion, fluctuations, and phase transitions. However quantitative and spatially resolved measurements remain challenging. Here we report a contactless, local, all-optical measurement of superconducting phase stiffness using propagating antiferromagnetic magnons as remote sensors. In CrSBr, strong exciton-magnon coupling enables optical excitation and detection of magnon wavepackets and precise determination of their group velocity. When CrSBr is interfaced with underdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$, we find that the magnon group velocity is substantially enhanced below the superconducting transition and quantitatively encodes the phase stiffness through Meissner screening currents. Using this capability, we identify a parallel-field-induced Berezinskii-Kosterlitz-Thouless transition through direct observation of the universal phase-stiffness jump, revealing a field-controlled route to expose intrinsic two-dimensional phase-ordering physics in a bulk cuprate. Our work establishes propagating magnons as local probes of superconducting electrodynamics and phase-coherent phenomena in low-dimensional quantum materials.
Source: arXiv (Cornell University)
Institutions: University of Washington, Lawrence Berkeley National Laboratory, University of Chemistry and Technology, Prague, Columbia University, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics, National Institute of Advanced Industrial Science and Technology, SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Stanford University, University of California, Berkeley
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: U.S. Department of Energy, Gordon and Betty Moore Foundation, University of Washington, Ministry of Education, Culture, Sports, Science and Technology, Ministerstvo Školství, Mládeže a Tělovýchovy, Office of Science, Multidisciplinary University Research Initiative, Basic Energy Sciences, Core Research for Evolutional Science and Technology, Air Force Office of Scientific Research, Division of Materials Sciences and Engineering
Awards: G1229526393, G1286236842, G1286251239, Next Generation of 2D Monoelemental Materials, G2371548206, G237429762, G2618837358, G2810384502, G2837468342, G303061748, G30714459, G3310577945, G3702897590, G4091144171, G419881185, G42916606, G4501827968, G495301720, G498139845, G5473946529, G5570207115, G650090426, G6550344761, G6652958823, G6902702339, G708600390, G7283024673, G791371132, Joseph Orenstein Experimental Investigator in Quantum Materials Award, G8382000481, Magnetic 2D/1D materials, their modification by electron beam and applications, G911061179
OpenAlex ID: W7220914396