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We study the heat transport due to phonons in nanomechanical structures using a phase space representation of non-equilibrium Green's functions. This representation accounts for the atomic degrees of freedom making it particularly suited…

Mesoscale and Nanoscale Physics · Physics 2017-10-10 Marcone I. Sena-Junior , Leandro R. F. Lima , Caio H. Lewenkopf

In this study, we use the transient thermal grating optical technique \textemdash a non-contact, laser-based thermal metrology technique with intrinsically high accuracy \textemdash to investigate room-temperature phonon-mediated thermal…

We present consistent results for molecular conduction using two central-complementary approaches: the non-equilibrium Green's function technique and the quantum master equation method. Our model describes electronic conduction in a…

Mesoscale and Nanoscale Physics · Physics 2016-04-13 Bijay Kumar Agarwalla , Dvira Segal

Computationally efficient modeling of the thermal conductivity of materials is crucial to thorough experimental planning and theoretical understanding of thermal properties. We present a modeling approach in this work that utilizes…

Mesoscale and Nanoscale Physics · Physics 2017-09-28 Long Chen , Jeffrey L. Braun , Brian F. Donovan , Patrick E. Hopkins , S. Joseph Poon

Nowadays, methods for analyzing light transmission through subwavelength structures are typically based on the mode expansion with Fourier series. However, these methods require sophisticated techniques and the solutions are in $k$-space,…

Computational Physics · Physics 2019-06-06 Jian-Shiung Hong , Kuan-Ren Chen

We have adapted R-matrix theory to calculate phonon scattering across systems of molecular to mesoscopic scale. The key novelty of this work is that the only required information about the scattering region are its normal modes, which are…

Mesoscale and Nanoscale Physics · Physics 2015-03-19 K. G. S. H. Gunawardana , Kieran Mullen

Increased power density in modern microelectronics has led to thermal management challenges which can cause degradation in performance and reliability. In many high-power electronic devices, the power consumption and heat removal are…

Mesoscale and Nanoscale Physics · Physics 2019-10-01 David B. Brown , Thomas L. Bougher , Xiang Zhang , Pulickel Ajayan , Baratunde A. Cola , Satish Kumar

An expression for the transmission matrix based conductance is provided for the propagation of scalar waves in certain bifurcated discrete waveguides using the paradigm of a three-terminal Landauer-Buttiker junction. It is found that the…

Mesoscale and Nanoscale Physics · Physics 2018-08-09 Basant Lal Sharma

Knowledge of the mean free path distribution of heat-carrying phonons is key to understanding phonon-mediated thermal transport. We demonstrate that thermal conductivity measurements of thin membranes spanning a wide thickness range can be…

Computationally inexpensive approximations describing electron-phonon scattering in molecular-scale conductors are derived from the non-equilibrium Green's function method. The accuracy is demonstrated with a first principles calculation on…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Magnus Paulsson , Thomas Frederiksen , Mads Brandbyge

Detailed understanding of vibrational heat transfer mechanisms between solids is essential for the efficient thermal engineering and control of nanomaterials. We investigate the frequency dependence of anharmonic scattering and interfacial…

Materials Science · Physics 2014-10-31 K. Sääskilahti , J. Oksanen , J. Tulkki , S. Volz

We extend concepts from microwave engineering to thermal interfaces and explore the principles of impedance matching in 1D. The extension is based on the generalization of acoustic impedance to non linear dispersions using the contact…

Mesoscale and Nanoscale Physics · Physics 2015-05-22 Carlos A. Polanco , Avik W. Ghosh

Heating and heat conduction in molecular junctions are considered within a general NEGF formalism. We obtain a unified description of heating in current carrying molecular junctions as well as the electron and phonon contributions to the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Michael Galperin , Mark A. Ratner , Abraham Nitzan

Utilizing the non-equilibrium Green's function method, we study the local heat current flow of phonons in nanoscale ballistic graphene nanoribbon, where boundary scattering leads to the formation of atomic-scale current vortices. We further…

Mesoscale and Nanoscale Physics · Physics 2024-07-23 Yin-jie Chen , Jing-tao Lü

Transient grating spectroscopy has emerged as a useful technique to study thermal phonon transport because of its ability to perform thermal measurements over length scales comparable to phonon mean free paths (MFPs). While several prior…

Mesoscale and Nanoscale Physics · Physics 2015-08-19 Austin J. Minnich

An efficient implicit kinetic scheme is developed to solve the stationary phonon Boltzmann transport equation (BTE) based on the non-gray model including the phonon dispersion and polarization. Due to the wide range of the dispersed phonon…

Computational Physics · Physics 2018-06-08 Chuang Zhang , Songze Chen , Zhaoli Guo

The lattice thermal conductivity of graphene is evaluated using a microscopic model that takes into account the lattice's discrete nature and the phonon dispersion relation within the Brillouin zone. The Boltzmann transport equation is…

Soft Condensed Matter · Physics 2024-01-18 J. Chen , Y. Liu

Charge and thermal conductivities are the most important parameters of carbon nanomaterials as candidates for future electronics. In this paper we address the effects of Anderson type disorder in long semiconductor carbon nanotubes (CNTs)…

Mesoscale and Nanoscale Physics · Physics 2013-10-16 H. Sevincli , T. Lehmann , D. A. Ryndyk , G. Cuniberti

Thermal transport in crystals is influenced by chemistry, boundaries, and nanostructure. The anharmonic phonon band structure extracted from molecular-dynamics simulations provides an illuminating view of both the type and extent of…

Mesoscale and Nanoscale Physics · Physics 2025-07-15 Albert Beardo , Prajit Rawte , Chia-Nien Tsai , Mahmoud I. Hussein

A transfer matrix method is developed for optical calculations of non-interacting graphene layers. Within the framework of this method, optical properties such as reflection, transmission and absorption for single-, double- and multi-layer…

Mesoscale and Nanoscale Physics · Physics 2013-05-10 Tianrong Zhan , Xi Shi , Yunyun Dai , Xiaohan Liu , Jian Zi