Triaxially strained suspended graphene for large-area pseudo-magnetic fields

TL;DR

This paper demonstrates a novel triaxially strained suspended graphene structure capable of generating large-area pseudo-magnetic fields, with potential applications in optoelectronics and graphene-based lasers.

Contribution

It provides the first experimental demonstration of triaxially strained graphene with large-scale pseudo-magnetic fields and proposes a photonic crystal laser structure utilizing these fields.

Findings

Pseudo-magnetic fields over micrometer-scale areas suggested by Raman and simulations.

Efficient current injection confirmed by current-voltage measurements.

Potential for optoelectronic applications and graphene lasers demonstrated.

Abstract

Strain-engineered graphene has garnered much attention recently owing to the possibilities of creating substantial energy gaps enabled by pseudo-magnetic fields. While theoretical works proposed the possibility of creating large-area pseudo-magnetic fields by straining monolayer graphene along three crystallographic directions, clear experimental demonstration of such promising devices remains elusive. Herein, we experimentally demonstrate a triaxially strained suspended graphene structure that has the potential to possess large-scale and quasi-uniform pseudo-magnetic fields. Our structure employs uniquely designed metal electrodes that function both as stressors and metal contacts for current injection. Raman characterization and tight-binding simulations suggest the possibility of achieving pseudo-magnetic fields over a micrometer-scale area. Current-voltage measurements confirm an efficient current injection into graphene, showing the potential of our devices for a new class of optoelectronic applications. We also theoretically propose a photonic crystal-based laser structure that obtains strongly localized optical fields overlapping with the spatial area under uniform pseudo-magnetic fields, thus presenting a practical route towards the realization of graphene lasers.