共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhongshui Ma 《Solid State Communications》2010,150(11-12):510-513
We predict an intrinsic thermo-spin Hall effect, namely, that a transverse spin current is generated by the temperature gradient and the heat current in a disorder-free two-dimensional electron gas (2DEG) with finite spin–orbit coupling. There exist two classes of contributions to the thermal spin Hall effect, corresponding to a 2DEG contacting two reservoirs at different temperatures and to a 2DEG separated from the reservoirs by insulating spacers, respectively. It is shown that the thermal spin Hall current can be generated not only by the temperature gradient directly but also by the thermoelectric effect. 相似文献
2.
Photographs of wasps or hornets, taken with different temperature sensitive infrared cameras, reveal body temperatures that are sometimes significantly lower than the ambient temperature. This suggests that the hornets possess an intrinsic biological heat pump mechanism which can be used to achieve such cooling. Evidence is presented to substantiate this novel suggestion and to argue that the heat pump is most likely implemented by exploiting a thermoelectric effect in the hornet cuticle. Such a natural heat pump can conceivably also serve to cool the active hornet, engaged in daytime activities outside the nest at ambient temperatures exceeding 40 degrees C, to a body temperature that is low enough to allow its survival in extreme thermal conditions. It might also function as a means of raising the body temperature up to a level that enables the hornet to remain active even when the ambient temperature is as low as 10 degrees C. 相似文献
3.
We propose a three-terminal heat engine based on semiconductor superlattices for energy harvesting. The periodicity of the superlattice structure creates an energy miniband, giving an energy window for allowed electron transport. We find that this device delivers a large power, nearly twice than the heat engine based on quantum wells, with a small reduction of efficiency. This engine also works as a refrigerator in a different regime of the system's parameters. The thermoelectric performance of the refrigerator is analyzed, including the cooling power and coefficient of performance in the optimized condition. We also calculate phonon heat current through the system and explore the reduction of phonon heat current compared to the bulk material. The direct phonon heat current is negligible at low temperatures, but dominates over the electronic at room temperature and we discuss ways to reduce it. 相似文献
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J. Krempaský 《Czechoslovak Journal of Physics》1964,14(7):533-554
A new method of measuring the thermal and thermoelectric characteristics of materials, especially semi-conductors, is elaborated theoretically and experimentally. Measurements are made in an unstationary regime on large enough samples (e.g. in liquids) but it is also possible to measure by stationary means. The contacts are either probes or linear. An especial advantage of the proposed methods is that they are quick, and, if linear wires are chosen as contacts, all the most important electrical, thermal and thermoelectric characteristics of materials can be measured in the same arrangement even up to high temperatures, and also in the liquid state after melting. In such an arrangement the conduction of heat by convection or radiation has no influence on the measurements. 相似文献
6.
A generalized multibaker map with periodic boundary conditions is shown to model boundary-driven transport, when the driving is applied by a perturbation of the dynamics localized in a macroscopically small region. In this case there are sustained density gradients in the steady state. A non-uniform stationary temperature profile can be maintained by incorporating a heat source into the dynamics, which deviates from the one of a bulk system only in a (macroscopically small) localized region such that a heat (or entropy) flux can enter an attached thermostat only in that region. For these settings the relation between the average phase-space contraction, the entropy flux to the thermostat and irreversible entropy production is clarified for stationary and non-stationary states. In addition, thermoelectric cross effects are described by a multibaker chain consisting of two parts with different transport properties, modeling a junction between two metals. 相似文献
7.
测量了准一维有机超导体(TMTSF)2ClO4单晶a方向不同降温速率下的高精度温差电动势(6—280K).高温下的温差电动势表现出线性行为,不能被正常的一维电子能带理论所解释.在240K左右观察到温差电动势斜率发生反常突变.在140K左右温差电动势向下逐渐偏离线性行为,这与1D—2D的维度渡越相关.对阴离子有序—无序相变温度Ta(Ta=24K)附近的温差电动势结果与比热和电阻率的数据进行了比较.对于极慢速降温的温差电动势,求导后可以看到相变的痕迹.随着通过Ta降温速率的增大,在Ta之下的温差电动势数值出现了一个逐渐增大的整体抬高.对此进行了讨论.
关键词:
低维体系
输运性质
温差电动势 相似文献
8.
V. F. Kharlamov 《Journal of Experimental and Theoretical Physics》2013,117(1):83-88
It is found that the dimensionless thermoelectric figure of merit of a material consisting of a large number of ball-shaped semiconductor or metal particles can be much more than unity. The introduction of an insulator into the space between the particles is shown to sharply increase the power of the converter of heat energy into electric current energy. 相似文献
9.
The thermoelectric effect in a quantum dot (QD) attached to two leads in the presence of microwave fields is studied by using the Keldysh nonequilibrium Green function technique. When the microwave is applied only on the QD and in the linear response regime, the main peaks in the thermoelectric figure of merit and the thermopower are found to decrease, with the emergence of a set of photon-induced peaks. Under this condition the microwave field cannot generate heat current or electrical bias voltage. Surprisingly, when the microwave field is applied only to one (bright) lead and not to the other (dark) lead or the QD, heat flows mostly from the dark to the bright lead, almost irrespective of the direction of the thermal gradient. We attribute this effect to microwave-induced opening of additional transport channels below the Fermi energy. The microwave field can change both the magnitude and the sign of the electrical bias voltage induced by the temperature gradient. 相似文献
10.
The effective properties of thermoelectric composites are well known to depend on boundary conditions, which causes the macro performance of thermoelectric composite to be difficult to assess. The overall macro-performance of multilayered thermoelectric medium is discussed in this paper. The analytical solutions are obtained, including the heat flux, temperature,electric potential, and the overall energy conversion efficiency. The results show that there are unique relationships between the temperature/electric potential and the electric current/energy flux in the material, and whether the material is independent of or embedded in thermoelectric composites. Besides, the Peltier effect at the interface can significantly improve the overall energy conversion efficiency of thermoelectric composites. These results provide a powerful tool to analyze the effective behaviors of thermoelectric composites. 相似文献
11.
Peter H. Handel 《Zeitschrift für Physik B Condensed Matter》1994,95(4):489-492
A new thermo-electrochemical effect similar to Peltier heat is introduced in this paper and suggested as a main cause of the excess heat observed in electrolytic cells. If the cell electrodes are made from different materials, we show that the system will function like a thermoelectric heat pump. With finite work input, this thermodynamic engine will pump in an infinite amount of low-grade environmental heat for vanishing temperature differences between the hot and cold source in the reversible, low current density, limit. A partial irreproducibility of excess heat observations is expected due to differences in the location of the calorimeter wall in each experiment. The heat pump nature and the thermoelectric properties of electrolytic cells are basic new notions introduced here. They may solve the excess heat paradox in electrolytic cold fusion, thus removing the well-known discrepancy between the small output of nuclear reaction products and the large excess heat, redefining this way both the notion of excess heat and the focus of our cold fusion research. 相似文献
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Nzar Rauf Abdullah 《Physics letters. A》2018,382(21):1432-1436
We report on calculation of spin-dependent thermal transport through a quantum ring with the Rashba spin-orbit interaction. The quantum ring is connected to two electron reservoirs with different temperatures. Tuning the Rashba coupling constant, degenerate energy states are formed leading to a suppression of the heat and thermoelectric currents. In addition, the quantum ring is coupled to a photon cavity with a single photon mode and linearly polarized photon field. In a resonance regime, when the photon energy is approximately equal to the energy spacing between two lowest degenerate states of the ring, the polarized photon field can significantly control the heat and thermoelectric currents in the system. The roles of the number of photon initially in the cavity, and electron–photon coupling strength on spin-dependent heat and thermoelectric currents are presented. 相似文献
14.
W. Felsch S. G. Kushnir K. Samwer H. Schröder R. van den Berg H. v. Löhneysen 《Zeitschrift für Physik B Condensed Matter》1982,48(2):99-107
The amorphous alloy Ce75.5Co24.5 prepared by melt spinning has been studied through measurements of the magnetic susceptibility, magnetization, electrical resistivity, thermoelectric power and specific heat. The results are interpreted in terms of a homogeneous intermediate valence state of the Ce ions. This is inferred from a temperature-independent magnetic susceptibility at low temperature and the absence of magnetic ordering, a large linear term in the specific heat, and aT
2 dependence of the electrical resistivity at low temperature followed by a steep increase with temperature up to 50 K. At this temperature, the thermoelectric power displays a maximum. The intrinsic properties are partially obscured at low temperatures by a contribution from roughly a few percent of magnetic impurities, presumably Ce3+ ions. They manifest themselves by an increase of the susceptibility towards low temperatures and by a broad Schottky-like contribution to the specific heat resulting from the excitation of magnetic clusters.Dedicated to Prof. Dr. S. Methfessel on the occasion of his 60th birthday 相似文献
15.
Boron and uranium form three metallic borides having the chemical formulae UB2, UB4 and UB12. In this study, we present the temperature variations of magnetic susceptibility, specific heat, electrical resistivity (performed in magnetic fields of 0 and up to 9 T), thermoelectric power and thermal conductivity measured on the bulk sample of UB12. This dodecaboride behaves as a typical metal, being a Pauli paramagnet and exhibiting a large variety of physical properties due to its specific close-packed structure containing B12 groups. We describe also an uncommon phenomenon observed in UB12, that is, a fairly large scattering of the experimental resistivity data under application of a magnetic field at low temperatures and its systematic vanishing during heating of the sample. This effect is probably caused by inharmonious movement (rattling) of the uranium atoms inside the oversized coordination cage, B24, reflected by applying the magnetic field. The specific heat, resistivity, thermoelectric power and heat transport data have been analysed in the framework of the low-frequency Einstein modes, which are mainly responsible for the phonon spectra behaviour in the system studied here. 相似文献
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E. Papp 《Zeitschrift für Physik B Condensed Matter》1984,55(1):17-22
An ac technique for the measurement of the thermoelectric power is introduced. This technique has the advantage, that it can be applied parallel with the heat capacity measurement on the same sample. The principle of the method and some technical details are presented. The method was used to measure the thermoelectric power (and specific heat) of single crystal Ni and Ni-1.5 w% Cu alloy near their Curie temperatures. The experimental data are compared with the resistive anomaly and specific heat and it is concluded that the behavior of the Seebeck coefficient is very similar to the resistive anomaly around the critical temperature.This work was carried out partly at the Materials Research Laboratory, Physics Department, University of Illinois, and supported in part by the National Science Foundation under Grant GH-33634 相似文献
18.
Xiaoguang Luo Nian Liu Jizhou He Teng Qiu 《Applied Physics A: Materials Science & Processing》2014,117(3):1031-1039
A numerical model of a nano-scaled thermoelectric heat engine with InP/InAs/InP trilayer quantum well (QW) is investigated. The expressions of those performance parameters, such as current, power output, and efficiency are expressed. By numerical calculation, the resonant tunneling behavior of electrons in the QW is described, which seems like a very good energy selective electron mechanism for the heat engine. After considering the radiation heat leakage, for fixed layer thicknesses of the QW, the optimum working regions of the heat engine with respect to the chemical potentials and the bias voltage are obtained numerically under the economic criterion. From these results, the power output can be increased by narrowing down the layer thicknesses. In addition, owing to the radiant heat leakage, the efficiency initially increases in the working regions and then decreases when the layer thicknesses increase gradually, from which one can obtain a maximum efficiency by optimizing layer thicknesses of QW. These results calculated here may provide a guide for the optimum designs of tunneling thermoelectric devices. 相似文献
19.
通过在互耦合外腔半导体激光器之间增加中继激光器,建立了一种链式互耦合半导体激光器混沌同步系统模型.理论分析了系统的实时混沌同步条件,数值研究了注入电流、互耦合条件、反馈条件等对系统实时混沌同步品质的影响,揭示了同步质量在反馈强度和互耦合强度二维参数空间的分布规律.结果表明:注入电流较大时,满足互耦合强度和反馈强度相同,互耦合延时和反馈延时相等,系统中所有激光器之间可同时实现稳定高品质实时混沌同步;中心激光器和边激光器之间的稳定实时混沌同步分布在在互耦合强度和反馈强度较小的区域以及互耦合强度和反馈强度相近的区域;边激光器之间由于同时接收到中心激光器实施的相同注入,能够较容易的实现稳定高品质的实时混沌同步.该系统可进一步扩展成为实现远距离的双向实时混沌同步或阵列激光器系统的实时混沌同步. 相似文献
20.
基于非平衡态格林函数方法,理论研究了与四个电极耦合的双量子点系统中的自旋和电荷能斯特效应,考虑了不同电极的磁动量结构和量子点内以及量子点间电子的库仑相互作用对热电效应的影响.结果表明铁磁端口中的磁化方向能够有效地调节能斯特效应:当电极1和电极3中的磁化方向反平行排列时,通过施加横向的温度梯度,系统中将会出现纯的自旋能斯特效应;当电极4从普通金属端口转变为铁磁金属端口时,将同时观测到电荷和自旋能斯特效应.研究发现,能斯特效应对于铁磁电极极化强度的依赖程度较弱,但对库仑排斥作用十分敏感.在量子点内和点间库仑排斥作用的影响下,自旋及电荷能斯特系数有望提高两个数量级. 相似文献