Strained graphene structures: from valleytronics to pressure sensing

Datum: 22 maart 2017

Locatie: Building U, room U.241 - Groenenborgerlaan 171 - 2020 Antwerpen

Tijdstip: 16 - 17 uur

Korte beschrijving: Condensed Matter Theory presented by Slavisa Milovanovic



Strained graphene structures: from valleytronics to pressure sensing

Abstract

Graphene can sustain a large amount of strain. Due to its strong bonds graphene can stretch up to 25% of its original size without breaking. Furthermore, those mechanical deformations lead to the generation of pseudo-magnetic fields (PMF) that can exceed 300 T. The generated PMF has the opposite direction for electrons originating from different valleys. We show that valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by a Gaussian-like deformation allows electrons from only one valley to transmit and a current of electrons from a single valley is generated at the opposite side of the locally strained region. We show that valley filtering is most effective with bumps of a certain height and width. Furthermore, applying a pressure difference between the two sides of a graphene membrane causes it to bend/bulge resulting in a resistance change. We find that the resistance changes linearly with pressure for bubbles of small radius while the response becomes non-linear for bubbles that stretch almost to the edges of the sample. This is explained as due to the strong interference of propagating electronic modes inside the bubble. Our calculations show that high gauge factors can be obtained in this way which makes graphene a good candidate for pressure sensing.



Contact e-mail: lucian.covaci@uantwerpen.be

Url: http://cmt.uantwerpen.be