We investigate the reflection near the reststrahlen band of the optical phonon in bulk GaAs in the time domain, using time-resolved terahertz spectroscopy. We find that the dynamics of the reflection measured for GaAs differs strongly from the reflection dynamics that would be expected for a TO phonon with a frequency-independent dephasing time.
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http://dx.doi.org/10.1364/ol.25.001609 | DOI Listing |
Sci Rep
December 2024
Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior, 474 011, India.
This study presents a comprehensive investigation into the intrinsic properties of RNiP (where R = Sm, Eu) filled skutterudite, employing the full-potential linearized augmented plane wave method within density functional theory (DFT) simulations using the WIEN2k framework. Structural, phonon stability, mechanical, electronic, magnetic, transport, thermal, and optical properties are thoroughly explored to provide a holistic understanding of these materials. Initially, the structural stability of SmNiP and EuNiP is rigorously evaluated through ground-state energy calculations obtained from structural optimizations, revealing a preference for a stable ferromagnetic phase over competing antiferromagnetic and non-magnetic phases.
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December 2024
Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang Province, China.
The solid-state integration of molecular electron spin qubits could promote the advancement of molecular quantum information science. With highly ordered structures and rational designability, microporous framework materials offer ideal matrices to host qubits. They exhibit tunable phonon dispersion relations and spin distributions, enabling optimization of essential qubit properties including the spin-lattice relaxation time (T) and decoherence time.
View Article and Find Full Text PDFACS Cent Sci
December 2024
Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States.
Spin-lattice relaxation constitutes a key challenge for the development of quantum technologies, as it destroys superpositions in molecular quantum bits (qubits) and magnetic memory in single molecule magnets (SMMs). Gaining mechanistic insight into the spin relaxation process has proven challenging owing to a lack of spectroscopic observables and contradictions among theoretical models. Here, we use pulse electron paramagnetic resonance (EPR) to profile changes in spin relaxation rates ( ) as a function of both temperature and magnetic field orientation, forming a two-dimensional data matrix.
View Article and Find Full Text PDFInt J Heat Mass Transf
March 2024
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, United States of America.
In classical theory, heat conduction in solids is regarded as a diffusion process driven by a temperature gradient, whereas fluid transport is understood as convection process involving the bulk motion of the liquid or gas. In the framework of theory, which is directly built upon quantum mechanics without relying on measured parameters or phenomenological models, we observed and investigated the fluid-like convective transport of energy carriers in solid heat conduction. Thermal transport, carried by phonons, is simulated in graphite by solving the Boltzmann transport equation using a Monte Carlo algorithm.
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December 2024
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Ultrafast thermal switches are pivotal for managing heat generated in advanced solid-state applications, including high-speed chiplets, thermo-optical modulators, and on-chip lasers. However, conventional phonon-based switches cannot meet the demand for picosecond-level response times, and existing near-field radiative thermal switches face challenges in efficiently modulating heat transfer across vacuum gaps. To overcome these limitations, we propose an ultrafast thermal switch design based on pump-driven transient polaritons in asymmetric terminals.
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