نتایج جستجو برای: thermal conductance
تعداد نتایج: 253105 فیلتر نتایج به سال:
We demonstrate that in the atomic-scale limit the thermal conductance K of the Fermi-Pasta-Ulam (FPU) model and its variants strongly deviates from the mesoscopic behavior due to the relevance of contact resistance. As a result, atomic chains follow log K=nu log T, where the power-law coefficient nu is exactly two times larger than the mesoscopic value. We smoothly interconnect the atomic and m...
Quantum physics predicts that there is a fundamental maximum heat conductance across a single transport channel and that this thermal conductance quantum, G(Q), is universal, independent of the type of particles carrying the heat. Such universality, combined with the relationship between heat and information, signals a general limit on information transfer. We report on the quantitative measure...
We have developed specially designed semiconductor devices for the measurement of thermal conductance in suspended nanostructures. By means of a novel subtractive comparison, we are able to deduce the phonon thermal conductance of individual nanoscale beams of different geometry and dopant profiles. The separate roles of important phonon scattering mechanisms are analyzed and a quantitative est...
Radiative heat exchange at the nanoscale presents a challenge for several areas due to its scope and nature. Here, we provide a thermokinetic description of microscale radiative energy transfer including phonon-photon coupling manifested through a non-Debye relaxation behavior. We show that a lognormal-like distribution of modes of relaxation accounts for this non-Debye relaxation behavior lead...
This paper illustrates an application of a technique for predicting the thermal characteristics of a bidirectional thermocycling device for polymerase chain reaction (PCR). The micromilling chamber is oscillated by a servo motor and contacted with different isothermal heating blocks to successfully amplify the DNA templates. Because a comprehensive database of contact resistance factors does no...
Thermal transport in Graphene is of great interest due to its high thermal conductivity, for both fundamental research and future applications such as heat dissipation in electronic devices. Although, the thermal conductivity of graphene can reduce depending on the coupling to the substrate [1]. In this work, we report high-resolution imaging of nanoscale thermal transport in single and few lay...
Thermal energy transport across the interfaces of physically and chemically modified graphene with two metals, Al and Cu, was investigated by measuring thermal conductance using the time-domain thermoreflectance method. Graphene was processed using a He2+ ion-beam with a Gaussian distribution or by exposure to ultraviolet/O3, which generates structural or chemical disorder, respectively. Hereby...
We report direct imaging of nanoscale thermal transport in single and few-layer graphene with approximately 50 nm lateral resolution using high vacuum scanning thermal microscopy. We observed increased heat transport in suspended graphene where heat is conducted by ballistic phonons, compared to adjacent areas of supported graphene, and observed decreasing thermal conductance of supported graph...
Transport in an ideal two-dimensional quantum spin Hall device is dominated by the counterpropagating edge states of electrons with opposite spins, giving the universal value of the conductance, 2e(2)/h. We study the effect on the conductance of a magnetic impurity, which can backscatter an electron from one edge state to the other. In the case of isotropic Kondo exchange we find that the corre...
This Letter reports on the influence of laser irradiation onto the electrical conductance of gold nanocontacts established with the mechanically controllable break-junction technique. We concentrate on the study of reversible conductance changes which can be as high as 200%. We investigate the dependence on the initial conductance of the contacts, and on the wavelength, the intensity, and the p...
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