Universal behavior of the bosonic metallic ground state in a two-dimensional superconductor

TL;DR

This study reveals a universal quantum bosonic metallic state in two-dimensional superconductors, characterized by a finite resistivity and emergent particle-hole symmetry, observed via gate and magnetic field tuning in LaAlO3/SrTiO3 interfaces.

Contribution

It demonstrates the universal behavior of the bosonic metallic ground state across different conditions, linking anomalous metal phases through a comprehensive phase diagram.

Findings

Anomalous metallic phases are connected in the phase diagram.

Resistivity shows linear dependence on magnetic field in the metallic state.

Hall resistivity diminishes, indicating emergent particle-hole symmetry.

Abstract

Anomalous metallic behavior, marked by a saturating finite resistivity much lower than the Drude estimate, has been observed in a wide range of two-dimensional superconductors. Utilizing the electrostatically gated LaAlO3/SrTiO3 interface as a versatile platform for superconductor-metal quantum phase transitions, we probe variations in the gate, magnetic field, and temperature to construct a phase diagram crossing from superconductor, anomalous metal, vortex liquid, to Drude metal states, combining longitudinal and Hall resistivity measurements. We find that the anomalous metal phases induced by gating and magnetic field, although differing in symmetry, are connected in the phase diagram and exhibit similar magnetic field response approaching zero temperature. Namely, within a finite regime of the anomalous metal state, the longitudinal resistivity linearly depends on field while the Hall resistivity diminishes, indicating an emergent particle-hole symmetry. The universal behavior highlights the uniqueness of the quantum bosonic metallic state, distinct from bosonic insulators and vortex liquids.