Engineering phonon transport in physical systems is a subject of interest in the study of materials, and has a crucial role in controlling energy and heat transfer. Of particular interest are non-reciprocal phononic systems, which in direct analogy to electric diodes, provide a directional flow of energy. Here, we propose an engineered nanostructured material, in which tunable non-reciprocal phonon transport is achieved through optomechanical coupling. Our scheme relies on breaking time-reversal symmetry by a spatially varying laser drive, which manipulates low-energy acoustic phonons. Furthermore, we take advantage of developments in the manipulation of high-energy phonons through controlled scattering mechanisms, such as using alloys and introducing disorder. These combined approaches allow us to design an acoustic isolator and a thermal diode. Our proposed device will have potential impact in phonon-based information processing, and heat management in low temperatures.
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http://dx.doi.org/10.1038/s41467-018-03624-y | DOI Listing |
Int 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.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and optoelectronic engineering, Shenzhen University, Shenzhen, 518060, P. R. China.
Crystalline thermoelectric materials, especially SnSe crystals, have emerged as promising candidates for power generation and electronic cooling. In this study, significant enhancement in ZT is achieved through the combined effects of lattice distortions and band convergence in multiple electronic valence bands. Density functional theory (DFT) calculations demonstrate that cation vacancies together with Pb substitutional doping promote the band convergence and increase the density of states (DOS) near the Fermi surface of SnSe, leading to a notable increase in the Seebeck coefficient (S).
View Article and Find Full Text PDFHigh-performance infrared light sources have significantly influenced the fields of photonics and optoelectronics. However, achieving infrared light emission with low energy consumption, high brightness, and rapid response remains a huge challenge. Single-walled carbon nanotubes (SWCNTs) could be an important candidate for infrared light emitters because of their superior electron mobility and phonon transport efficiency.
View Article and Find Full Text PDFACS Omega
December 2024
Research Center for Advanced Computing Infrastructure, JAIST, 1-1 Asahidai, Nomi 923-1211, Ishikawa, Japan.
There has been a marked increase in interest in high-temperature superconductors over the past few years, sparked by their potential to revolutionize multiple fields, including energy generation and transportation. A particularly promising avenue of exploration has emerged in the form of ternary superhydrides, compounds composed of hydrogen along with two other rare-earth elements. Our investigation focuses on the search for Y-Th-H ternary compounds; employing an evolutionary search methodology complemented by electron-phonon calculations reveals a stable superhydride, 6̅2-YThH, capable of exhibiting a critical temperature ( ) as high as 222 K at 200 GPa along a few low- novel hydrides.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
School of Physical and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
Molten salts are important in a number of energy applications, but the fundamental mechanisms operating in ionic liquids are poorly understood, particularly at higher temperatures. This is despite their candidacy for deployment in solar cells, next-generation nuclear reactors, and nuclear pyroprocessing. We perform extensive molecular dynamics simulations over a variety of molten chloride salt compositions at varying temperature and pressures to calculate the thermodynamic and transport properties of these liquids.
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