Nonlinear Phononics in the Two-Dimensional Magnet CrSBr
POSTER
Abstract
Magnetism in two-dimensional (2D) van der Waals (vdW) crystals offers promising directions for low-dimensional physics and devices. CrSBr is a novel 2D vdW semiconductor that has received intense research interest due to its strain-dependent, low-dimensional magnetic properties. Mega-electron volt (MeV) ultrafast electron diffraction (UED) revealed that fs optical pump pulses excited non-equilibrium atomic displacements observed as coherent acoustic phonons (CAPs). Analyzing Bragg peak intensities allowed the determination of GHz-frequency acoustic disturbances propagating parallel to the surface normal and anisotropic phonon dynamics in the a-b plane. The temperature and crystallographic dependence of the phonons suggest that antiferromagnetic ordering influences the phonon oscillatory behavior. We observed subharmonic phonon frequencies which suggest a nonlinear oscillatory coupling between the laser-induced pump phonons and the secondary, subharmonic phonons. Thus, CrSBr was found to serve as a nonlinear phononic frequency conversion material. Our work provides a foundation for exploring how fs light pulses can influence phonon dynamics in materials with strong spin-lattice coupling. These results suggest that CAPs can be tuned by the sample dimension to match the magnon frequencies and show the promise of CrSBr for use in optical-to-microwave transducers and phononic devices.
*This work has been supported under Contract No. DE-SC0012704 with the U.S. DOE Office and the U.S. AFOSR and the Clarkson Aerospace Corp. under Award FA9550-21-1-0460. B.F. acknowledges Welch Foundation (Grant No. L-E-001-19921203) and the TcSUH. A.M.R. and J.J.B. acknowledge the support from European Union (ERC-2021-StG 101042680 2D-SMARTiES awarded to J.J.B.), the Spanish MICINN (Excellence Unit María de Maeztu CEX2019-000919-M), and the Generalitat Valenciana (CDEIGENT/2019/022); A.M.R. thanks the Spanish MIU (Grant No FPU21/04195). The work at University of Washington is supported by AFOSR FA9550-19-1-0390 and FA9550-21-1-0460.
Publication:A manuscript of this work is submitted to AIP's Structural Dynamics Journal. The title of the manuscript is: Ultrafast-induced Coherent Acoustic Phonons in the Two-dimensional Magnet CrSBr
Presenters
Jayajeewana Niranjana Ranhili Pelige
University of Houston
Authors
Jayajeewana Niranjana Ranhili Pelige
University of Houston
Sumit Khadka
University of Houston
Junjie Li
Brookhaven National Laboratory Collider-Accelerator Department
