More Like this

1. Phonon Dephasing Dynamics in MoS ₂

   https://doi.org/10.1021/acs.nanolett.0c04368  

   Sun, Liuyang; Kumar, Parveen; Liu, Zeyu; Choi, Junho; Fang, Bin; Roesch, Sebastian; Tran, Kha; Casara, Joshua; Priego, Eduardo; Chang, Yu-Ming; et al (February 2021, Nano Letters)

   null (Ed.)
2. Magnon-phonon hybridization in 2D antiferromagnet MnPSe ₃

   https://doi.org/10.1126/sciadv.abj3106  

   Mai, Thuc T.; Garrity, Kevin F.; McCreary, Amber; Argo, Joshua; Simpson, Jeffrey R.; Doan-Nguyen, Vicky; Aguilar, Rolando Valdés; Walker, Angela R. (October 2021, Science Advances)

   Magnetic excitations in van der Waals (vdW) materials, especially in the two-dimensional (2D) limit, are an exciting research topic from both the fundamental and applied perspectives. Using temperature-dependent, magneto-Raman spectroscopy, we identify the hybridization of two-magnon excitations with two phonons in manganese phosphorus triselenide (MnPSe 3 ), a magnetic vdW material that hosts in-plane antiferromagnetism. Results from first-principles calculations of the phonon and magnon spectra further support our identification. The Raman spectra’s rich temperature dependence through the magnetic transition displays an avoided crossing behavior in the phonons’ frequency and a concurrent decrease in their lifetimes. We construct a model based on the interaction between a discrete level and a continuum that reproduces these observations. Our results imply a strong hybridization between each phonon and a two-magnon continuum. This work demonstrates that the magnon-phonon interactions can be observed directly in Raman scattering and provides deep insight into these interactions in 2D magnetic materials. 

   more » « less
3. Brillouin zone center phonon modes in ZnGa ₂ O ₄

   https://doi.org/10.1063/5.0012526  

   Stokey, Megan; Korlacki, Rafał; Knight, Sean; Hilfiker, Matthew; Galazka, Zbigniew; Irmscher, Klaus; Darakchieva, Vanya; Schubert, Mathias (August 2020, Applied Physics Letters)

   null (Ed.)
4. Twist-engineered phonon polaritons in α − V ₂ O ₅

   https://doi.org/10.1364/OL.557267  

   Shiravi, H.; Zheng, W.; He, Y.; Ran, S.; Rhodes, D_A; Balicas, L.; Zhou, H_D; Ni, G_X (April 2025, Optics Letters)

   The advent of layered materials has unveiled new opportunities for tailoring electromagnetic waves at the subwavelength scale, particularly through the study of polaritons, a hybrid light–matter excitation. In this context, twist-optics, which investigates the optical properties of twisted stacks of van der Waals (vdW) layered specimens, has emerged as a powerful tool. Here, we explore the tunability of phonon polaritons in α-V₂O₅via interlayer twisting using scanning nano-infrared (IR) imaging. We show that the polaritonic response can be finely adjusted by varying their interlayer electromagnetic coupling, allowing for precise control over the propagation direction and phase transition from open unidirectional iso-frequency contours to closed elliptic geometries. Our experimental results, in conjugate with theoretical modeling, reveal the mechanisms underpinning this tunability, highlighting the role of twist-induced nano-light modifications for advanced nanophotonic control at the nanoscale. 

   more » « less
5. Anomalous phonon relaxation in Au ₃₃₃ (SR) ₇₉ nanoparticles with nascent plasmons

   https://doi.org/10.1073/pnas.1904337116  

   Higaki, Tatsuya; Zhou, Meng; He, Guiying; House, Stephen D.; Sfeir, Matthew Y.; Yang, Judith C.; Jin, Rongchao (July 2019, Proceedings of the National Academy of Sciences)

   Research on plasmons of gold nanoparticles has gained broad interest in nanoscience. However, ultrasmall sizes near the metal-to-nonmetal transition regime have not been explored until recently due to major synthetic difficulties. Herein, intriguing electron dynamics in this size regime is observed in atomically precise Au 333 (SR) 79 nanoparticles. Femtosecond transient-absorption spectroscopy reveals an unprecedented relaxation process of 4–5 ps—a fast phonon–phonon relaxation process, together with electron–phonon coupling (∼1 ps) and normal phonon–phonon coupling (>100 ps) processes. Three types of –R capped Au 333 (SR) 79 all exhibit two plasmon-bleaching signals independent of the –R group as well as solvent, indicating plasmon splitting and quantum effect in the ultrasmall core of Au 333 (SR) 79 . This work is expected to stimulate future work on the transition-size regime of nanometals and discovery of behavior of nascent plasmons. 

   more » « less