Ultrafast nonlinear phonon response of few-layer hexagonal boron nitride

Taehee Kang (1) , Jia Zhang (1) , Achintya Kundu (1) , Klaus Reimann (1) , Michael Woerner (1) , Thomas Elsaesser (1) , Bernard Gil (2) , Guillaume Cassabois (2) , Christos Flytzanis (3) , Giorgia Fugallo (4) , Michele Lazzeri (5) , Ryan Page (6) , Debdeep Jena (6)

1 MBI - Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie
2 L2C - Laboratoire Charles Coulomb
3 Nano-Optique
4 LTeN - Laboratoire de Thermique et d’Energie de Nantes
5 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
6 Cornell University [New York]

Nonequilibrium dynamics of TO phonons and low-frequency interlayer shear modes are mapped in femtosecond mid-infrared pump-probe experiments. Time-resolved changes of TO phonon absorption reveal a TO phonon lifetime of 1.2 ps, while the low-frequency excitations decay with a time constant of approximately 20 ps. The coupling of intralayer TO and interlayer motions manifests in a quasi-instantaneous redshift of the TO phonon resonance by some 10 cm −1. Theoretical calculations account for the coupling scenario and underline the relevance of inter-phonon interactions for the nonlinear phonon response of few-layer materials.

Domaines: Matière Condensée [cond-mat]

Taehee Kang, Jia Zhang, Achintya Kundu, Klaus Reimann, Michael Woerner, et al.. Ultrafast nonlinear phonon response of few-layer hexagonal boron nitride. Physical Review B, 2021, 104 (14), pp.L140302. ⟨10.1103/PhysRevB.104.L140302⟩. ⟨hal-03374670⟩