The temperature distribution in nanowires due to Joule heating is studied analytically using a continuum model and a Green's function approach. We show that the temperatures reached in nanowires can be much lower than that predicted by bulk models of Joule heating, due to heat loss at the nanowire surface that is important at nanoscopic dimensions, even when the thermal conductivity of the environment is relatively low. In addition, we find that the maximum temperature in the nanowire scales weakly with length, in contrast to the bulk system. A simple criterion is presented to assess the importance of these effects. The results have implications for the experimental measurements of nanowire thermal properties, for thermoelectric applications, and for controlling thermal effects in nanowire electronic devices.
The domain wall depinning from a notch in a Permalloy nanostrip on top of a ${\rm SiO_2/Si}$ substrate is studied theoretically under application of static magnetic fields and the injection of short current pulses. The influence of Joule heating on current-induced domain wall depinning is explored self-consistently by coupling the magnetization dynamics in the ferromagnetic strip to the heat transport throughout the system. Our results indicate that Joule heating plays a remarkable role in these processes, resulting in a reduction in the critical depinning field and/or in a temporary destructi…
Using full-band electron and phonon dispersion relation, we investigate the temperature dependence of Joule heating in Zigzag Graphene Nanoribbons under high-field. At different temperatures of 300 K, 600 K, and 900 K, the Joule heating always increases linearly with time or the power is a constant. Although the scattering rates at 900 K and 600 K are 113 and 55 times higher than that of 300 K, the Joule heating power of 900 K and 600 K are just 12.6 and 6.7 timers higher than that of 300 K.
The theoretical formula for the entropy production rate in the presence of spin current is derived using the spin-dependent transport equation and thermodynamics. This theory is applicable regardless of the source of the spin current, for example, an electric field, a temperature gradient, or the Hall effect. It reproduces the result in a previous work on the dissipation formula when the relaxation time approximation is applied to the spin relaxation rate. By using the developed theory, it is found that the dissipation in spin Hall geometry has a contribution proportional to the square of the …
A programmable micromechanical resonator based on a VO2 thin film is reported. Multiple mechanical eigenfrequency states are programmed using Joule heating as local power source, gradually driving the phase transition of VO2 around its Metal-Insulator transition temperature. Phase coexistence of domains is used to tune the stiffness of the device via local control of internal stresses and mechanical properties. This study opens perspectives for developing mechanically configurable nanostructure arrays.
Nonlinear devices, such as transistors, enable contemporary computing technologies. We theoretically investigate nonlinear effects, bearing a high fundamental scientific and technical relevance, in magnonics with emphasis on superconductor-ferromagnet hybrids. Accounting for finite magnon chemical potential, we theoretically demonstrate magnonic spin-Joule heating, the spin analogue of conventional electronic Joule heating. Besides suggesting a key contribution to magnonic heat transport in a broad range of devices, it provides insights into the thermal physics of non-conserved bosonic excitat…
This work investigates nanosecond superparamagnetic switching in 50 nm diameter in-plane magnetized magnetic tunnel junctions (MTJs). Due to the small in-plane uniaxial anisotropy, dwell times below 10 ns and auto-correlation times down to 5 ns are measured for circular superparamagnetic tunnel junctions (SMTJs). SMTJs exhibit probabilistic switching of the magnetic free layer, which can be used for the generation of true random numbers. The quality of random bitstreams, generated by our SMTJ, is evaluated with a statistical test suite (NIST STS, sp 800-22) and shows true randomness after thre…
Pulsed domain wall movement is studied here in Ni80Fe20 nanowires on SiO2, using a fully integrated electrostatic, thermoelectric, and micromagnetics solver based on the Landau-Lifshitz-Bloch equation, including Joule heating, anisotropic magneto-resistance, and Oersted field contributions. During the applied pulse the anisotropic magneto-resistance of the domain wall generates a dynamic heat gradient which increases the current-driven velocity by up to 15%. Using a temperature-dependent conductivity significant differences are found between the constant voltage-pulsed and constant current-pul…
Manipulating materials at the nanometer scale is challenging, particularly if alignment with nanoscale electrodes is desired. Here we describe a lithography-free, self-aligned nanotrench ablation (SANTA) technique to create nanoscale trenches in a polymer like poly(methyl) methacrylate (PMMA). The nanotrenches are self-aligned with carbon nanotube (CNT) and graphene ribbon electrodes through a simple Joule heating process. Using simulations and experiments we investigate how the Joule power, ambient temperature, PMMA thickness, and substrate properties can improve the spatial resolution of thi…
Graphene oxide (GO) is reduced by Joule heating using in-situ transmission electron microscopy (TEM). The approach allows the simultaneous study of GO conductivity by electrical measurements and of its composition and structural properties throughout the reduction process by TEM, electron diffraction and electron energy-loss spectroscopy. The small changes of GO properties observed at low applied electric currents are attributed to the promotion of diffusion processes. The actual reduction process starts from an applied power density of about 2 1014 Wm-3 and occurs in a highly uniform and loca…
We consider the heat equation for monolayer two-dimensional materials in the presence of heat flow into a substrate and Joule heating due to electrical current. We compare devices including a nanowire of constant width and a bow tie (or wedge) constriction of varying width, and we derive approximate one-dimensional heat equations for them; a bow tie constriction is described by the modified Bessel equation of zero order. We compare steady state analytic solutions of the approximate equations with numerical results obtained by a finite element method solution of the two-dimensional equation. Us…
Joule heating and electronic Gurzhi effect in hydrodynamic differential transport in an electron liquid
State Key Laboratory of Semiconductor Physics and Chip Technologies, Institute of Semiconductors, Chinese Academy of Science（中国科学院半导体研究所半导体物理与芯片技术国家重点实验室）；College of Material Science and Opto-Electronic Technology, University of Chinese Academy of Sciences（中国科学院大学物质科学与光电技术学院）；Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所北京凝聚态物理国家研究中心）；Center for Quantum Matters, School of Physics, Zhejiang University（浙江大学物理学院量子物质中心）；CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences（中国科学院大学拓扑量子计算卓越创新中心）
Recently the memristive electrical transport properties in NbO$_2$ have attracted much attention for their promising application to the neuromorphic computation. At the center of debates is whether the metal-to-insulator transition (MIT) originates from the structural distortion (Peierls) or the electron correlation (Mott). With inputs from experiments and first principles calculations, we develop a thermodynamical model rooted in the scenario of the MIT driven by a $2^{nd}$ order Peierls instability. We find that the temperature dependence of the electrical conductivity can be accurately fit …
The origin of hysteresis in resistive switching in magnetite is Joule heating
在许多过渡金属氧化物中，观察到电阻经历由大偏压引起的剧烈变化。在磁铁矿中，Fe $_3$ O $_4$，低于Verwey温度，最近发现一个电场驱动的过渡到一个较低的电阻状态，具有滞后的电流-电压响应。本文报道了外延磁铁矿薄膜的脉冲电导测量结果。我们发现，虽然高到低电阻的转变是由电场驱动的，在$I-V$曲线中观察到的滞后的结果从焦耳加热在低电阻状态。磁滞回线的形状取决于脉冲参数，并减少到一个无电流的“跳跃”提供的热弛豫是快速的电压脉冲之间的时间相比。提出了一个简单的弛豫时间热模型，捕捉的滞后机制的要点。
During the standard ac lock-in measurement of the resistance of a two-dimensional electron gas (2DEG) applying an ac current $I = \sqrt{2} I_0 \sin(ωt)$, the electron temperature $T_e$ oscillates with the angular frequency $2 ω$ due to the Joule heating $\propto I^2$. We have shown that the highest ($T_\mathrm{H}$) and the lowest ($T_\mathrm{L}$) temperatures during a cycle of the oscillations can be deduced, at cryogenic temperatures, exploiting the third-harmonic (3$ω$) component of the voltage drop generated by the ac current $I$ and employing the amplitude of the Shubnikov-de Haas oscillat…
We consider the Johnson noise of a two-dimensional, two-terminal electrical conductor for which the electron system obeys the Wiedemann-Franz law. We derive two simple and generic relations between the Johnson Noise temperature and the heat flux into the electron system. First, we consider the case where the electron system is heated by Joule heating from a DC current, and we show that there is a universal proportionality coefficient between the Joule power and the increase in Johnson noise temperature. Second, we consider the case where heat flows into the sample from an external source, and …
We study, both theoretically and experimentally, the features on the current-voltage characteristic of a highly transparent Josephson junction caused by transition of the superconducting leads to the normal state. These features appear due to the suppression of the Andreev excess current. We show that by tracing the dependence of the voltage, at which the transition occurs, on the bath temperature and by analyzing the suppression of the excess current by the bias voltage one can recover the temperature dependence of the heat flow out of the junction. We verify theory predictions by fabricating…
We present a time-resolved study of the DC-current driven magnetization dynamics in a microstructured Cr/Heusler/Pt waveguide by means of Brillouin light scattering. A reduction of the effective spin-wave damping via the spin-transfer-torque effect leads to a strong increase in the magnon density. This is accompanied by a decrease of the spin-wave frequencies. By evaluating the time scales of these effects, the origin of this frequency shift can be identified. However, recently, we found that the experimental setup partially influences the decay of the spin-wave intensity after the current pul…
Electrons in graphene exhibit hydrodynamic behavior in a certain range of temperatures. We indicate that electric current in this regime can result in cooling of electron fluid due to the Joule-Thomson effect. Cooling occurs in the Fermi liquid regime, while for the Dirac fluid the effect results in heating.
Inelastic electron tunneling and surface-enhanced optical spectroscopies at the molecular scale require cryogenic local temperatures even under illumination - conditions that are challenging to achieve with plasmonically resonant metallic nanostructures. We report a detailed study of the laser heating of plasmonically active nanowires at substrate temperatures from 5 to 60 K. The increase of the local temperature of the nanowire is quantified by a bolometric approach and could be as large as 100 K for a substrate temperature of 5 K and typical values of laser intensity. We also demonstrate tha…
We have employed noise thermometry for investigations of thermal relaxation between the electrons and the substrate in nanowires patterned from 40-nm-thick titanium film on top of silicon wafers covered by a native oxide. By controlling the electronic temperature $T_e$ by Joule heating at the base temperature of a dilution refrigerator, we probe the electron-phonon coupling and the thermal boundary resistance at temperatures $T_e= 0.5 - 3$ Kelvin. Using a regular $T^5$-dependent electron-phonon coupling of clean metals and a $T^4$-dependent interfacial heat flow, we deduce a small contribution…
The thermoelectric properties of a nanoscale germanium segment connected by aluminium nanowires are studied using scanning thermal microscopy. The germanium segment of 168\,nm length features atomically sharp interfaces to the aluminium wires and is surrounded by an Al$_2$O$_3$ shell. The temperature distribution along the self-heated nanowire is measured as a function of the applied electrical current, for both Joule and Peltier effects. An analysis is developed that is able to extract the thermal and thermoelectric properties including thermal conductivity, the thermal boundary resistance to…
Heat Conduction and Energy Relaxation in an InAs Nanowire Approaching the Clean One-Dimensional Limit
Lund University（隆德大学）；Indian Institute of Technology Kanpur（坎普尔印度理工学院）；Aalto University School of Science（阿尔托大学理学院）；University of Chicago（芝加哥大学）；SUSTech（南方科技大学）
Heat dissipation and its relation to thermopower in single-molecule junctions
受最近实验的启发[Lee et al.Nature 498，209（2013）]，我们在此提出了载流单分子结中焦耳加热的详细理论分析。通过结合量子输运的Landauer方法与从头计算，我们展示了如何加热的分子结的电极是由它的电子结构。特别是，我们表明，在一般情况下，热量是不相等的结的两个电极中耗散，它取决于偏置极性（或等效的电流方向）。这些加热不对称性与结的热电势密切相关，因为这两个量都由非常相似的原理控制。我们通过分析基于具有不同锚定基团的苯衍生物的单分子结来说明这些想法。热耗散和热功率之间的密切关系提供了探索基本现象的一般策略，如珀尔帖效应或量子干涉效应对分子传输结焦耳加热的影响。
Based on spin-dependent transport theory and thermodynamics, we develop a generalized theory of the Joule heating in the presence of a spin current. Along with the conventional Joule heating consisting of an electric current and electrochemical potential, it is found that the spin current and spin accumulation give an additional dissipation because the spin-dependent scatterings inside bulk and ferromagnetic/nonmagnetic interface lead to a change of entropy. The theory is applied to investigate the dissipation due to pure spin-current generated by spin pumping across a ferromagnetic/nonmagneti…
Photo-bolometric effect is critically important in optoelectronic structures and devices employing metallic electrodes with nanoscale features due to heating caused by the plasmonic field enhancement. One peculiar case is individual silver nanowires (Ag NWs) and their networks. Ag NW-networks exhibit excellent thermal, electrical, and mechanical properties, providing a simple yet reliable alternative to common flexible transparent electrode materials used in optoelectronic devices. To date there have been no reports on the photoresponse of Ag NWs. In this work, we show that a single Ag NW and …
