Quasiparticle and superfluid dynamics in Magic-Angle Graphene


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Date

2025-05-08

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

Magic-Angle Twisted Bilayer Graphene (MATBG) shows a wide range of correlated phases which are electrostatically tunable. Despite a growing knowledge of the material, there is yet no consensus on the microscopic mechanisms driving its superconducting phase. A major obstacle to progress in this direction is that key thermodynamic properties, such as specific heat, electron-phonon coupling and superfluid stiffness, are challenging to measure due to the 2D nature of the material and its relatively low energy scales. Here, we use a gate-defined, radio frequency-biased, Josephson junction to probe the electronic dynamics of MATBG. We demonstrate evidence for two processes determining the low-frequency dynamics across the phase diagram: thermalization of electronic quasiparticles through phonon scattering and inductive response of the superconducting condensate. A phenomenological approach allows us to relate the experimentally observed dynamics to several thermodynamic properties of MATBG, including electron-phonon coupling and superfluid stiffness. Our findings support anisotropic or nodal superconductivity in MATBG and demonstrate a broadly applicable method for studying properties of 2D materials with out-of-equilibrium nanodevice dynamics.

Publication status

published

Editor

Book title

Volume

16 (1)

Pages / Article No.

4273

Publisher

Nature

Event

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Organisational unit

03439 - Ensslin, Klaus / Ensslin, Klaus check_circle
08835 - Ihn, Thomas (Tit.-Prof.) check_circle
02205 - FIRST-Lab / FIRST Center for Micro- and Nanoscience check_circle

Notes

Funding

951541 - Entropy in engineered quantum systems — Mesoscopic thermodynamics of correlated quantum states (EC)
862660 - Toward new era of quantum electrical measurements through phase slips (EC)
185902 - QSIT - Quantum Science and Technology (SNF)

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