Circuit QED detection of induced two-fold anisotropic pairing in a hybrid superconductor-ferromagnet bilayer

Abstract

Hybrid systems represent one of the frontiers in the study of unconventional superconductivity and are a promising platform to realize topological superconducting states. Owing to their mesoscopic dimensions, these materials are challenging to probe using many conventional measurement techniques, and require new experimental probes to successfully characterize. In this work, we develop a probe that enables us to measure the superfluid density of micron-size superconductors using microwave techniques drawn from circuit quantum electrodynamics (cQED). We apply this technique to a paradigmatic hybrid system, the superconductor/ferromagnet bilayer, and find that the proximity-induced superfluid density is two-fold anisotropic within the plane of the sample and exhibits power law temperature-scaling which is indicative of a nodal superconducting state. These experimental results are consistent with the theoretically predicted signatures of induced triplet pairing with a nodal $p$-wave order parameter. Moreover, we unexpectedly observe drastic modifications to the microwave response at frequencies near the ferromagnetic resonance, suggesting a coupling between the spin dynamics and induced superconducting order in the ferromagnetic layer. Our results offer new insights into the unconventional superconducting states induced in superconductor/ferromagnet heterostructures and simultaneously establish a new avenue for the study of fragile unconventional superconductivity in low-dimensional materials such as van der Waals heterostructures.

7 main text pages + 4 supplemental text pages, 4 main text figures + 4 supplemental figures

References in corpus (10)

• Non-Abelian Anyons and Topological Quantum Computation
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Strongly coupled magnons and cavity microwave photons
• Hybridizing ferromagnetic magnons and microwave photons in the quantum limit
• A spin triplet supercurrent through the half-metallic ferromagnet CrO2
• Magnetic Penetration Depth in Unconventional Superconductors
• Isospin magnetism and spin-triplet superconductivity in Bernal bilayer graphene
• The Order Parameter for the Superconducting Phases of UPt${}_3$
• Detecting induced $p\pm ip$ pairing at the Al-InAs interface with a quantum microwave circuit
• Superfluid density of superconductor-ferromagnet bilayers

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