Discovery and Manipulation of a Single Polaron in a Monolayer Mott Insulator

Abstract

Polarons are quasiparticles composed of excess electrons and local lattice distortions that are crucial for understanding many-body physics. However, atomic-scale observation and manipulation of an intrinsic polaron in strongly correlated systems still remain elusive. Here, we report the discovery and manipulation of a single polaron in single-layer Mott insulator 1T-TaSe2 by employing low-temperature scanning tunneling microscopy (STM). We observed a polaronic state located near the lower Hubbard band accompanied by a weakening of the Hubbard band. The polaron resulted in an upward bending of the Hubbard band, which signifies a local doping effect. Remarkably, the polaron can be reversibly generated, annihilated, and moved by the STM tip. Furthermore, first-principles calculations reveal that an excess electron couples to the surrounding lattice within a charge-density-wave cell to form a small polaron. Our work provides key insights into intrinsic small polarons in strongly correlated systems and demonstrates a route toward the atomic-scale manipulation of individual polarons.