Oscillations of van Hove singularities spacing induced by sub-Angstrom fluctuations of interlayer spacing in graphene superlattices

TL;DR

This study shows that sub-Angstrom fluctuations in interlayer spacing of twisted bilayer graphene, induced by STM tip pulses, cause large, slow oscillations in van Hove singularities, enabling dynamic tuning of vdWs properties.

Contribution

Demonstrates that STM tip pulses can induce sub-Angstrom interlayer fluctuations in TBG, causing oscillations in van Hove singularities and enabling dynamic control of vdWs structures.

Findings

Sub-Angstrom interlayer fluctuations can be induced by STM tip pulses.

Oscillations in van Hove singularities spacing have periods of 500-1000 seconds.

Tip-induced local stress affects the electronic properties of TBG.

Abstract

Physical properties of two-dimensional van der Waals (vdWs) structures depend sensitively on both stacking orders and interlayer interactions. Yet, in most cases studied to date, the interlayer interaction is considered to be a static property of the vdWs structures. Here we demonstrate that applying a scanning tunneling microscopy (STM) tip pulse on twisted bilayer graphene (TBG) can induce sub-Angstrom fluctuations of the interlayer separation in the TBG, which are equivalent to dynamic vertical external pressure of about 10 GPa on the TBG. The sub-Angstrom fluctuations of the interlayer separation result in large oscillations of the energy separations between two van Hove singularities (VHSs) in the TBG. The period of the oscillations of the VHSs spacing is extremely long, about 500-1000 seconds, attributing to tip-induced local stress in the atomic-thick TBG. Our result provides an efficient method to tune and measure the physical properties of the vdWs structures dynamically.