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Nanostructured materials exhibit low thermal conductivity because of the additional scattering due to phonon-boundary interactions. As these interactions are highly sensitive to the mean free path (MFP) of a given phonon mode, MFP…

Materials Science · Physics 2016-01-13 Giuseppe Romano , Keivan Esfarjani , David A. Strubbe , David Broido , Alexie M. Kolpak

We present a new method for predicting effective thermal conductivity ($\kappa_{\textrm{eff}}$) in materials, informed by ${ab\,initio}$ material property simulations. Using the Boltzmann transport equation in a Self-Adjoint Angular Flux…

Materials Science · Physics 2019-08-22 Jackson R. Harter , Aria Hosseini , Todd. S. Palmer , P. Alex Greaney

The phonon Boltzmann transport equation (BTE) is a powerful tool for studying non-diffusive thermal transport. Here, we develop a new universal variational approach to solving the BTE that enables extraction of phonon mean free path (MFP)…

Mesoscale and Nanoscale Physics · Physics 2016-04-13 Vazrik Chiloyan , Lingping Zeng , Samuel Huberman , Alexei A. Maznev , Keith A. Nelson , Gang Chen

The broadband and ultrafast photoresponse of graphene has been extensively studied in recent years, although the photoexcited carrier dynamics is still far from being completely understood. Different experimental approaches imply either one…

Mesoscale and Nanoscale Physics · Physics 2017-08-22 Sergey Menabde , Hyunwoo Cho , Namkyoo Park

The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their…

Mesoscale and Nanoscale Physics · Physics 2015-12-23 Thu Trang Nghiem Thi , P. -Olivier Chapuis

We investigate the aspects of the electron transport in the zigzag graphene nanoribbons (ZGNRs) using the non-equilibrium Green's function (NEGF) formalism. The latter is an esoteric tool in mesoscopic physics and using this tool the…

Strongly Correlated Electrons · Physics 2019-06-03 Pankaj Bhalla , Surender Pratap

To elucidate the relationship between a crystal's structure, its thermal conductivity, and its phonon dispersion characteristics, an analysis is conducted on layered diatomic Lennard-Jones crystals with various mass ratios. Lattice dynamics…

Materials Science · Physics 2007-05-23 A. J. H. McGaughey , M. I. Hussein , E. S. Landry , M. Kaviany , G. M. Hulbert

One way to reduce the lattice thermal conductivity of solids is to induce additional phonon surface scattering through nanostructures. However, how phonons interact with boundaries, especially at the atomic level, is not well understood. In…

Mesoscale and Nanoscale Physics · Physics 2017-11-15 Cheng Shao , Qingyuan Rong , Ming Hu , Hua Bao

The Boltzmann transport equation is one of the most relevant framework to study the heat transport at the nanoscale, beyond the diffusive regime and up to the micrometer-scale. In the general case of three-dimensional devices, the particle…

Mesoscale and Nanoscale Physics · Physics 2018-12-05 B. Davier , J. Larroque , P. Dollfus , L. Chaput , S. Volz , D. Lacroix , J. Saint-Martin

We report finite-volume simulations of the phonon Boltzmann transport equation (BTE) for heat conduction across the heterogeneous interfaces in SiGe superlattices. The diffuse mismatch model incorporating phonon dispersion and polarization…

Mesoscale and Nanoscale Physics · Physics 2010-05-17 Dhruv Singh , Jayathi Y. Murthy , Timothy S. Fisher

We report an unambiguous phonon resonance effect originating from germanium nanoparticles embedded in silicon matrix. Our approach features the combination of phonon wave-packet method with atomistic dynamics and finite element method…

Computational Physics · Physics 2017-12-05 Lei Feng , Takuma Shiga , Haoxue Han , Shenghong Ju , Yuriy A. Kosevich , Junichiro Shiomi

By way of the nonequilibrium Green's function simulations and first principles calculations, we report that borophene, a single layer of boron atoms that was fabricated recently, possesses an extraordinarily high lattice thermal conductance…

Materials Science · Physics 2017-05-31 Hangbo Zhou , Yongqing Cai , Gang Zhang , Yong-Wei Zhang

Understanding ballistic phonon transport effects in transient thermoreflectance experiments and explaining the observed deviations from classical theory remains a challenge. Diffusion equations are simple and computationally efficient but…

Mesoscale and Nanoscale Physics · Physics 2016-03-23 Jesse Maassen , Mark Lundstrom

There is still a gap in understanding phonons scattering by geometrical defects at the nanoscale, and it remains a significant challenge for heat transfer management in nanoscale devices and systems. In this study, we aim to explore the…

Mesoscale and Nanoscale Physics · Physics 2024-03-19 Mykola Isaiev , Nataliia Kyrychenko , Vasyl Kuryliuk , David Lacroix

The thermal interface conductance between Al and Si was simulated by a non-equilibrium molecular dynamics method. In the simulations, the coupling between electrons and phonons in Al are considered by using a stochastic force. The results…

We investigate the effect of vibrational degrees of freedom on the linear thermoelectric transport through a single-level quantum dot described by the spinless Anderson-Holstein impurity model. To study the effects of strong electron-phonon…

Strongly Correlated Electrons · Physics 2017-11-30 A. Khedri , V. Meden , T. A. Costi

Defects can significantly degrade the thermal conductivity of ThO2, an advanced nuclear fuel material as well as a surrogate for other fluorite-structured materials. We investigate how point defects in ThO2 impact phonon mode-resolved…

Materials Science · Physics 2024-09-24 Beihan Chen , Linu Malakkal , Marat Khafizov , David H. Hurley , Miaomiao Jin

In this paper, we present a powerful method (Atomistic Green's Function, AGF) for calculating the effective Hamiltonian of acoustic and elastic wave-scatterers. The ability to calculate the effective Hamiltonian allows for the study of…

Applied Physics · Physics 2024-04-30 Hossein Khodavirdi , Zhun-Yong Ong , Ankit Srivastava

Phonon reflection and transmission at the interfaces plays a fundamental role in cryogenic particle detectors, in which the optimization of the phonon signal at the sensor (in case of phonon-mediated detectors) or the minimization of the…

Instrumentation and Detectors · Physics 2019-06-19 M. Martinez , L. Cardani , N. Casali , A. Cruciani , G. Pettinari , M. Vignati

The impact of dispersion relations, anisotropy, and Brillouin zone structure on intrinsic phonon scattering rates has been assessed within the harmonic approximation-perturbation theory approach for lattice dynamics. Anisotropic nonlinear…

Materials Science · Physics 2022-06-15 Ahmed Hamed , Anter El-Azab