In Situ Electric Tuning―An Emerging STM Tactic for Probing Exotic Quantum Materials

ABSTRACT

In situ electric tuning (ISET) integrated with scanning tunneling microscopy and spectroscopy (STM/STS) has established itself as a highly effective methodology for controlling quantum electronic states in low‐dimensional materials. This approach combines the sub‐atomic spatial resolution and meV‐resolved spectroscopic capability of STM with the reversible and continuously tunable carrier modulation of field‐effect device architectures. To date, this approach has been applied to numerous systems, including graphene‐based van der Waals heterostructures, correlated electron systems, and moiré superlattice systems hosting emergent quantum phases. Herein, we systematically summarize the state‐of‐the‐art experimental implementations, including global electrostatic gating, tip‐induced local gating, tip‐induced voltage pulse, and in‐plane electric tuning, accompanied with distinct physics under each configuration. We then highlight key representative advances in resolving gate‐dependent band renormalization, correlated insulating states, charge ordering, symmetry breaking, and electrically driven metastable phases at the nanoscale. We discuss practical limitations, such as restricted carrier‐density ranges, tip‐induced perturbations, dielectric reliability, and challenges in decoupling electric effects from current injection and Joule heating. Looking forward, we outline future directions in device engineering, including programmable local electrostatics, scalable architectures, and integrated platforms for operando studies, highlighting their potential to enable deterministic control of emergent quantum phases in functional materials.