Signatures of a strange metal in a bosonic system

Metals have the distinguishing characteristic of an electrical resistivity that decreases with decreasing temperature T. Within Fermi liquid theory, which forms the basis for our understanding of ordinary metals, their resistance arises from the scattering of well-defined quasiparticles at a rate following 1/τ ~ T² in the low temperature limit. Various quantum materials^1–15, notably high-temperature superconductors^1–10, however, exhibit metallic behavior that deviates from this central paradigm. The resistivities of these strange metals imply a scattering rate that is linear in temperature, which renders the assumption of long-lived quasiparticles at low T problematic. Moreover, the bounded slope of the T-linear resistance in fermionic strange metal is linked to the so-called Planckian dissipation^3,11,16,17, which lends strange metals a surprising link to black holes, gravity, and quantum information theory^18-20. Here we show the unexpected appearance of strange metal signatures in a bosonic system for which the quasiparticle concept does not apply. Our nanopatterned YBa₂Cu₃O_7−δ (YBCO) film arrays reveal signatures of T-linear resistance as well as B-linear resistance over an extended temperature and magnetic field range in various samples. Strikingly, below the onset temperature  at which Cooper pairs form, the low-field magnetoresistance oscillates with a period dictated by the superconducting flux quantum of h/2e where e is the electron charge and h is the Planck constant. Simultaneously, the Hall coefficient R_H drops and vanishes within the measurement resolution with decreasing temperature. These two signatures indicate that Cooper pairs instead of single electrons dominate the transport process and the system is bosonic. By extending the reach of strange metal phenomenology to a bosonic system, our results suggest that there is a fundamental principle governing their transport which transcends particle statistics.