Control of Elementary Excitations by Acoustic Fields

Interaction of surface acoustic waves with epitaxial graphene

Two opposite interdigital transducers (IDTs) generate surface acoustic waves (SAWs) at a fixed resonant frequency of the microwaves applied to them. The SAWs then induce an electric current in the graphene layer whose polarity depends on the propagation direction of the SAW.

Graphene is emerging as an important material for electronic applications due to its two dimensional, planar character and high carrier mobility, which persists up to room temperatures. These favourable properties open the way for exploring carrier control processes alternative to the direct application of electric fields. A particularly interesting approach employs the strain and piezoelectric fields generated by a surface acoustic wave (SAW). The moving and tuneable character of these fields allow for the effective capture of carriers and their transport at the well-defined velocity of the SAW.

 

This project investigates the interaction of SAWs with epitaxial graphene layers grown on SiC. SAWs modulate the graphene band structure and interact strongly with carriers. We explore these features for the controlled transport of carriers and spins in graphene layers. This, in turn, requires a better knowledge of the momentum transfer process from SAWs to carriers in graphene, as well as the effect of the SAW-induced strain and piezoelectric fields into the electronic band structure and spin-splitting.

 

Graphene is also a promising candidate for spin information transport. The use of ferromagnetic source and drain contacts allows spin injection into and extraction from a graphene channel for acoustic transport. Together with the fast, well-defined SAW velocity and the long spin decoherence times expected in graphene, such an approach should allow acoustic spin transport along distances of hundreds of micrometers.

 

This project is inserted within the Priority Program 1459 "Graphene" of the Deutsche Forschungsgemeinschaft (DFG).

Selected Publications

2 Author A. Hernández-Mínguez , A. Tahraoui , J. M. J. Lopes , P. V. Santos
Title

Acoustoelectric transport at gigahertz frequencies in coated epitaxial graphene

Source Appl. Phys. Lett. , 108 , 193502 ( 2016 )
DOI : 10.1063/1.4949756 | Download: PDF | 2779 Cite : Bibtex RIS
A. Hernández-Mínguez, A. Tahraoui, J. M. J. Lopes, and P. V. Santos

1 Author P. V. Santos , T. Schumann , M. H. Oliveira Jr. , J. M. J. Lopes , H. Riechert
Title

Acousto-electric transport in epitaxial monolayer graphene on SiC

Source Appl. Phys. Lett. , 102 , 221907 ( 2013 )
Download: PDF | 2405 Cite : Bibtex RIS
P. V. Santos, T. Schumann, M. H. Oliveira Jr., J. M. J. Lopes, and H. Riechert

Contact

Dr. Paulo V. Santos

Senior Scientist

+49 30 20377-221

lab: -360, -340, -343

santos@pdi-berlin.de