Microscopic evolution of doped Mott insulators from polaronic metal to Fermi liquid

TL;DR

This study uses cold-atom quantum simulation to observe the doping-induced transition from a polaronic metal to a Fermi liquid in Mott insulators, revealing changes in correlations and magnetic fluctuations.

Contribution

First experimental observation of the microscopic crossover from polaronic metal to Fermi liquid in doped Mott insulators using cold-atom quantum simulators.

Findings

Crossover occurs around 30% hole doping.

Transformation of multi-point correlations with doping.

Emergence of incommensurate magnetic fluctuations.

Abstract

The competition between antiferromagnetism and hole motion in two-dimensional Mott insulators lies at the heart of a doping-dependent transition from an anomalous metal to a conventional Fermi liquid. Condensed matter experiments suggest charge carriers change their nature within this crossover, but a complete understanding remains elusive. We observe such a crossover in Fermi-Hubbard systems on a cold-atom quantum simulator and reveal the transformation of multi-point correlations between spins and holes upon increasing doping at temperatures around the superexchange energy. Conventional observables, such as spin susceptibility, are furthermore computed from the microscopic snapshots of the system. Starting from a magnetic polaron regime, we find the system evolves into a Fermi liquid featuring incommensurate magnetic fluctuations and fundamentally altered correlations. The crossover is completed for hole dopings around $30\%$. Our work benchmarks theoretical approaches and discusses possible connections to lower temperature phenomena.