Pseudomagnetic Fields in a Locally Strained Graphene Drumhead

TL;DR

This paper investigates how localized strain from an STM tip induces pseudomagnetic fields in graphene, confining charge carriers and enabling quantum dot formation, with simulations clarifying key parameters affecting this process.

Contribution

It provides a systematic coarse-grained simulation study of STM tip-induced strain in graphene, elucidating how tip position, size, and voltage influence pseudomagnetic fields and quantum dot creation.

Findings

Strain and pseudomagnetic fields depend on tip position relative to graphene center.

Tip size and graphene dimensions significantly affect the induced fields.

Back-gate voltage modulates the strain and pseudomagnetic field strength.

Abstract

Recent experiments reveal that a scanning tunneling microscopy (STM) probe tip can generate a highly localized strain field in a graphene drumhead, which in turn leads to pseudomagnetic fields in the graphene that can spatially confine graphene charge carriers in a way similar to a lithographically defined quantum dot (QD). While these experimental findings are intriguing, their further implementation in nanoelectronic devices hinges upon the knowledge of key underpinning parameters, which still remain elusive. In this paper, we first summarize the experimental measurements of the deformation of graphene membranes due to interactions with the STM probe tip and a back gate electrode. We then carry out systematic coarse grained, (CG), simulations to offer a mechanistic interpretation of STM tip-induced straining of the graphene drumhead. Our findings reveal the effect of (i) the position of the STM probe tip relative to the graphene drumhead center, (ii) the sizes of both the STM probe tip and graphene drumhead, as well as (iii) the applied back-gate voltage, on the induced strain field and corresponding pseudomagnetic field. These results can offer quantitative guidance for future design and implementation of reversible and on-demand formation of graphene QDs in nanoelectronics.