Superfluid stiffness of twisted trilayer graphene superconductors

Abhishek Banerjee, Zeyu Hao, Mary Kreidel, Patrick Ledwith, Isabelle Phinney, Jeong Min Park, Andrew Zimmerman, Marie E. Wesson, Kenji Watanabe, Takashi Taniguchi, Robert M. Westervelt, Amir Yacoby, Pablo Jarillo-Herrero, Pavel A. Volkov, Ashvin Vishwanath, Kin Chung Fong (k.fong@northeastern.edu) and Philip Kim (pkim@physics.harvard.edu)
Additional contact information
Abhishek Banerjee: Harvard University
Zeyu Hao: Harvard University
Mary Kreidel: Harvard University
Patrick Ledwith: Harvard University
Isabelle Phinney: Harvard University
Jeong Min Park: Massachusetts Institute of Technology
Andrew Zimmerman: Harvard University
Marie E. Wesson: Harvard University
Kenji Watanabe: National Institute for Materials Science
Takashi Taniguchi: National Institute for Materials Science
Robert M. Westervelt: Harvard University
Amir Yacoby: Harvard University
Pablo Jarillo-Herrero: Massachusetts Institute of Technology
Pavel A. Volkov: Harvard University
Ashvin Vishwanath: Harvard University
Kin Chung Fong: RTX BBN Technologies
Philip Kim: Harvard University

Nature, 2025, vol. 638, issue 8049, 93-98

Abstract: Abstract The robustness of the macroscopic quantum nature of a superconductor can be characterized by the superfluid stiffness, ρs, a quantity that describes the energy required to vary the phase of the macroscopic quantum wavefunction. In unconventional superconductors, such as cuprates, the low-temperature behaviour of ρs markedly differs from that of conventional superconductors owing to quasiparticle excitations from gapless points (nodes) in momentum space. Intensive research on the recently discovered magic-angle twisted graphene family has revealed, in addition to superconducting states, strongly correlated electronic states associated with spontaneously broken symmetries, inviting the study of ρs to uncover the potentially unconventional nature of its superconductivity. Here we report the measurement of ρs in magic-angle twisted trilayer graphene (TTG), revealing unconventional nodal-gap superconductivity. Utilizing radio-frequency reflectometry techniques to measure the kinetic inductive response of superconducting TTG coupled to a microwave resonator, we find a linear temperature dependence of ρs at low temperatures and nonlinear Meissner effects in the current-bias dependence, both indicating nodal structures in the superconducting order parameter. Furthermore, the doping dependence shows a linear correlation between the zero-temperature ρs and the superconducting transition temperature Tc, reminiscent of Uemura’s relation in cuprates, suggesting phase-coherence-limited superconductivity. Our results provide strong evidence for nodal superconductivity in TTG and put strong constraints on the mechanisms of these graphene-based superconductors.

Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/s41586-024-08444-3 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:638:y:2025:i:8049:d:10.1038_s41586-024-08444-3

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/s41586-024-08444-3

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla (sonal.shukla@springer.com) and Springer Nature Abstracting and Indexing (indexing@springernature.com).