Recent years have witnessed the boom of cavity optomechanics, which exploits the confinement and coupling of optical and mechanical waves at the nanoscale. Among their physical implementations, optomechanical (OM) crystals built on semiconductor slabs enable the integration and manipulation of multiple OM elements in a single chip and provide gigahertz phonons suitable for coherent phonon manipulation. Different demonstrations of coupling of infrared photons and gigahertz phonons in cavities created by inserting defects on OM crystals have been performed. However, the considered structures do not show a complete phononic bandgap, which should enable longer lifetimes, as acoustic leakage is minimized. Here we demonstrate the excitation of acoustic modes in a one-dimensional OM crystal properly designed to display a full phononic bandgap for acoustic modes at 4 GHz. The modes inside the complete bandgap are designed to have high-mechanical Q-factors, limit clamping losses and be invariant to fabrication imperfections.
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Phys Chem Chem Phys
January 2025
Theoretical Physics Section, Bhabha Atomic Research Centre, Mumbai-400085, India.
Extensive research on ultrashort laser-induced melting of noble metals like Au, Ag and Cu is available. However, studies on laser energy deposition and thermal damage of their alloys, which are currently attracting interest for energy harvesting and storage devices, are limited. This study investigates the melting damage threshold (DT) of three intermetallic alloys of Au and Cu (AuCu, AuCu and AuCu) subjected to single-pulse femtosecond laser irradiation, comparing them with their constituent metals.
View Article and Find Full Text PDFSci Rep
January 2025
Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, ul. Grudziądzka 5, 87-100, Toruń, Poland.
Due to their simple structure (two bond species randomly arranged on a cubic lattice), the zincblende ABC semiconductor alloys (zb-SCA) set a benchmark to explore how physical properties are impacted by disorder. A longstanding controversy was whether the lattice dynamics (phonons), governed by the bond force constant, i.e.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Mechanical Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
The intrinsic temperature dependence of Raman-active modes in carbon nanotubes (CNTs), particularly the radial breathing mode (RBM), has been a topic of a long-standing controversy. In this study, we prepared suspended individual CNTs to investigate how their Raman spectra depend on temperature and to understand the effects of environmental conditions on this dependency. We analyzed the intrinsic temperature dependence of the main Raman-active modes, including the RBM, the moiré-activated R feature, and the G-band in double-walled carbon nanotubes (DWCNT) and single-walled carbon nanotubes (SWCNTs) after complete desorption of air.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Stanford Institute for Materials and Energy Sciences, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025.
Recent experiments suggest a new paradigm toward novel colossal magnetoresistance (CMR) in a family of materials EuM[Formula: see text]X[Formula: see text] (M [Formula: see text] Cd, In, Zn; X [Formula: see text] P, As), distinct from the traditional avenues involving Kondo-Ruderman-Kittel-Kasuya-Yosida crossovers, magnetic phase transitions with structural distortions, or topological phase transitions. Here, we use angle-resolved photoemission spectroscopy and density functional theory calculations to explore their origin, particularly focusing on EuCd[Formula: see text]P[Formula: see text]. While the low-energy spectral weight royally tracks that of the resistivity anomaly near the temperature with maximum magnetoresistance ([Formula: see text]) as expected from transport-spectroscopy correspondence, the spectra are completely incoherent and strongly suppressed with no hint of a Landau quasiparticle.
View Article and Find Full Text PDFNat Commun
November 2024
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
Density wave (DW) order is believed to be correlated with superconductivity in the recently discovered high-temperature superconductor LaNiO. However, experimental investigations of its evolution under high pressure are still lacking. Here, we explore the quasiparticle dynamics in bilayer nickelate LaNiO single crystals using ultrafast optical pump-probe spectroscopy under high pressures up to 34.
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