Event Details

Coherent phononics in Two-dimensional van der Waals materials by Wenjing Yan, University of Nottingham

Date: 28th April 2023, 3pm

Location: C036

Two-dimensional van der Waals (2D-vdW) are layered materials that consist of strong intralayer chemical bonds and weak interlayer vdW forces. The highly anisotropic nature of these materials has allowed for many discoveries, such as single atomic layers by mechanical exfoliation, quantum confinement, superior elastic properties and new properties in twisted layers. Coherent THz and sub-THz phonons, which carry dynamical strain, could bring useful insight to the classical and quantum phenomena in this class of material with the unexplored picosecond temporal and nanometre spatial resolutions.

Our experimental technique includes a pump-probe setup with microscope objective for imaging ultrasonic signal. This allows us to probe phonons in both time and spatial domains non-destructively. Using this technique, we demonstrate the capability of phonons to reveal fundamental properties of vdW materials, for example, the strength of interlayer and intralayer bonding which are critical for the design and assembly of vdW heterostructures [1,2]. By fabricating a hybrid nanostructure, we can generate and detect propagating coherent phonons modes with frequencies up to tens of GHz [3]. Our findings open up new exciting directions for the exploitation of phonon hybridization with other elemental excitations like spin, photon and magnon.

[1] J. D. G. Greener, et al. ACS Nano, 13,11530 (2019)

[2] W. Yan et al. Adv. Funct. Mater. 31, 2106206 (2021)

[3] W. Yan, et.al, Nano Lett. 22, 6509 (2022).