Superconductor–Insulator Transition Induced by Precise Subtripled Vapor Chemical Gating

Recent progress in superconductor–insulator transition has shed light on the intermediate metallic state with unique electronic inhomogeneity. The microscopic model, suggesting that carrier spatial distribution plays a decisive role in the intermediate state, has been instrumental in understanding the quantum transition. However, the narrow carrier density window in which the intermediate state exists necessitates precise control of the gate dielectric layer, presenting a challenge to in situ map the carrier spatial distribution. Herein, a subtripled vapor chemical gating strategy has been proposed to precisely control carrier density and map spatial distribution in the LixZrNCl system. The chemical gating strategy utilizes subtripled vapor to quasi-continuously reduce the Li doping level, driving the ground-state transition from superconductor to quantum metal to quantum Griffiths singularity (QGS) to insulator. In situ optical mapping demonstrates an inhomogeneous electronic state in the intermediate metallic state and an evolution to a stripe-like pattern at 4 K, offering new insights into the nature of the intermediate metallic state.