Signatures of a strange metal in a bosonic system
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<strong>Metals have the distinguishing characteristic of an electrical resistivity that decreases with decreasing temperature <em>T.</em> 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/</strong><strong><em>τ</em></strong><strong> ~ <em>T</em><sup>2</sup> in the low temperature limit. Various quantum materials<sup>1–15</sup>, notably high-temperature superconductors<sup>1–10</sup>, 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 <em>T</em> problematic. Moreover, the bounded slope of the <em>T</em>-linear resistance in fermionic strange metal is linked to the so-called </strong><strong>Planckian dissipation<sup>3,11,16,17</sup>, which lends strange metals a surprising link to black holes, gravity, and quantum information theory<sup>18-20</sup>. Here we show the unexpected appearance of strange metal signatures in a bosonic system for which the quasiparticle concept does not apply. Our nanopatterned YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−δ</sub> (YBCO) film arrays reveal signatures of <em>T</em>-linear resistance as well as <em>B</em>-linear resistance over an extended temperature and magnetic field range in various samples. Strikingly, below the onset temperature </strong> <strong> at which Cooper pairs form, the low-field magnetoresistance oscillates with a period dictated by the superconducting flux quantum of <em>h</em>/2<em>e</em> where <em>e</em> is the electron charge and <em>h</em> is the Planck constant. Simultaneously, the Hall coefficient <em>R</em><sub>H</sub> 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. </strong><strong>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.</strong>
