Unique Quantum Metallic State in Ti₂O₃/GaN

Abstract

The emergence of quantum metallic state marked by a saturating finite electrical resistance in the zero-temperature limit in a variety of 2D superconductors injects an exciting momentum into the realm of heterostructure superconductivity. Despite much research effort over the last few decades, there is not yet a general consensus on the nature of this unexpected quantum metal. Here, we report the observation of a unique quantum metallic state within the hallmark of Bose-metal in Ti 2 O 3 /GaN. Remarkably, the quantum bosonic metallic state continuously tuned by a magnetic field in the vicinity of the two-dimensional superconductivitymetal transition persists in the normal phase, indicating the existence of composite bosons formed by electron Cooper pairs even in the normal phase. Our findings provide distinct evidence for electron pairing in the normal phase of heterointerface superconductors and shed fresh light on the pairing nature underlying heterointerface superconductivity.