Coupling a Mobile Hole to an Antiferromagnetic Spin Background: Transient Dynamics of a Magnetic Polaron

• Published in: Physical review. X 2021-04, Vol.11 (2), p.021022, Article 021022
• Main Authors: Ji, Geoffrey, Xu, Muqing, Kendrick, Lev Haldar, Chiu, Christie S., Brüggenjürgen, Justus C., Greif, Daniel, Bohrdt, Annabelle, Grusdt, Fabian, Demler, Eugene, Lebrat, Martin, Greiner, Markus
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Condensed matter physics; Coupling; Cuprates; Density; Dopants; Electrons; Elementary excitations; Equilibrium; High temperature; Magnetic properties; Magnetism; Polarons; Spin dynamics; Spin exchange; Superconductivity; Two dimensional models
• ISSN: 2160-3308; 2160-3308
• DOI: 10.1103/PhysRevX.11.021022

Understanding the interplay between charge and spin and its effects on transport is a ubiquitous challenge in quantum many-body systems. In the Fermi-Hubbard model, this interplay is thought to give rise to magnetic polarons, whose dynamics may explain emergent properties of quantum materials such as high-temperature superconductivity. In this work, we use a cold-atom quantum simulator to directly observe the formation dynamics and subsequent spreading of individual magnetic polarons. Measuring the density- and spin-resolved evolution of a single hole in a 2D Hubbard insulator with short-range antiferromagnetic correlations reveals fast initial delocalization and a dressing of the spin background, indicating polaron formation. At long times, we find that dynamics are slowed down by the spin exchange time, and they are compatible with a polaronic model with strong density and spin coupling. Our work enables the study of out-of-equilibrium emergent phenomena in the Fermi-Hubbard model, one dopant at a time.