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We report a simple and accurate method to address the inevitable radiative heat loss in the Thomson coefficient measurement. The additional steps required are the measurement of the Joule heat arising from the ac current, measurement of the electrical resistance of the sample, and calculation of the ratio of the two measurement signals arising from the Joule and Thomson effects. The underlying concept is that most of the radiative heat loss that occurs during the measurement of Joule and Thomson heats can be compensated for by calculating the ratio of the two signals. This is because the heat loss during the Joule heat measurement will be highly similar to that during the Thomson heat measurement. Heat transfer analysis indicates that radiative heat loss is reduced by at least a factor of six. Once the Thomson coefficient is measured, accurate Seebeck and Peltier coefficients can be obtained in a single run. This approach was demonstrated by performing measurements on fine platinum wires in the temperature range of 80 K–300 K. The difference between the compensated and uncompensated curves became significant as the temperature increased; moreover, this difference was proportional to the cube of the temperature for a long fine-wire sample, where there is substantial radiative heat loss. Thus, the proposed approach is completely different from a conventional one, wherein the measurement accuracy degrades owing to inevitable radiative heat loss without prior knowledge of the thermal conductivity and emissivity of the sample.

We investigate the origin of the variation in resistive switching hysteresis of VO2 thin films. Using pulsed electrical measurements in textured VO2 thin film devices, we show that the hysteresis observed in I–V curves results from Joule heating effects, particularly in the low-resistance state. The hysteresis is reduced by increasing the cooling time between pulses. Based on a mechanism of Joule heating-induced metal-insulator transition, numerical simulations are performed, which agree with the experimental variation in the hysteresis. Finally, a framework for engineering the I–V curves of VO2 devices is proposed.

The interband optical conductivity of undoped graphene gives only 2.3% absorption of light regardless of the light frequency. In this work, we show that by enhancing the electric field on a graphene surface through the interference effect, the light absorption of an undoped monolayer graphene can be much enhanced up to 50%. The monolayer graphene is put at the center of a specially designed multilayer structure of dielectric media. The enhanced absorption can be achieved for any arbitrary frequency by changing the number of layers or the refractive index of the layers. We also show that the absorption of light is used by Joule's heating of graphene which can be applied for local heating by light.

We report on a memory device concept based on the recently discovered unidirectional spin Hall magnetoresistance (USMR), which can store multiple bits of information in a single ferromagnetic heterostructure. We show that the USMR with possible contribution of Joule heating-driven magnetothermal effects in ferromagnet/normal metal/ferromagnet (FM/NM/FM) trilayers gives rise to four different 2nd harmonic resistance levels corresponding to four magnetization states ( ⇉, ⇄, ⇆, ⇇) in which the system can be found. Combined with the possibility of controlling the individual FMs by spin-orbit torques, we propose that it is possible to build an all-electrical lateral two-terminal multi-bit-per-cell memory device.

We show the electric-field induced magnetization switching for CoFeB/MgO magnetic tunnel junctions with thick MgO barrier layer of 2.8 nm, whose resistance-area product is 176 kΩ μm2, and achieve the small switching energy of 6.3 fJ/bit. The increase of the junction resistance is expected to suppress the energy consumption due to the Joule heating during the switching; however, the energy is still dominated by the Joule energy rather than the charging energy. This is because the junction resistance decreases more rapidly for junctions with thicker MgO as bias voltage increases.

We address experimental and theoretical study of a two-dimensional electron gas transport at low and moderate electric fields. The devices under study are group-III nitride-based (AlGaN/GaN) gateless heterostructures grown on sapphire. The transmission line model patterns of different channel lengths, L, and of the same channel width are used. A strong dependence of the device I-V characteristics on the channel length has been found. We have developed a simple theoretical model to adequately describe the observed peculiarities in the I-V characteristics measured in steady-state and pulsed (10(-6) s) regimes. The effect of the Joule heating of a heterostructure is clearly distinguished. The thermal impedance and the channel temperature rise caused by the Joule self-heating have been extracted for the devices of different L at different values of dissipated power. The current reduction due to both self-heating and hot-electron effects is determined quantitatively as a function of the electric field. (C) 2003 American Institute of Physics.

A receiver for digital optical inputs is presented which is based on a differential pair of optical thyristors. Modification of the conventional differential pair allows the electrical readout of its ON and OFF states. Optical input pulses with an energy of about 3 femto-Joule (at a wavelength of 830 nm) are sufficiently large for detection. In its present size, the receiver works up to 155 Mbit/s.

We measure power dissipation in phase change memory (PCM) devices by scanning Joule ex-pansion microscopy (SJEM) with ~50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding effects. Comparison of SJEM and electrical characterization with simulations of the PCM devices uncovers a thermopower ~350 uV/K for 25 nm thick films of face centered-cubic crystallized GST, and contact resistance ~2.0 x 10^-8 Ohm-m2. Knowledge of such nanoscale Joule, Peltier, and current crowding effects is essential for energy-efficient design of future PCM technology., includes supplement

The transient electroforming process of TiO2-based resistive switching devices is investigated using a pulsed voltage method, and the electroforming time is found to vary from 10−8 s to 10−1 s as function of pulse magnitude (3–8 V) and ambient temperature (25–100 °C). Pulsed experiments and thermal simulations reveal that Joule self-heating has a significant effect on the electroforming dynamics, specially for electroforming voltages above 5.5 V where there is little dependence on ambient temperature and the electroforming time (10–100 ns) is much shorter than the device thermal time constant (≈2 μs).

This letter reports on an investigation of dc current-voltage measured in CaCu3Ti4O12 ceramics. The experimental results show unusual I-V behaviors associated with the electrically inhomogeneous nature of the grains (mixture of semiconducting and insulating regions) and dependence on delay time. The data strongly suggest that both the localization of current in the conductive region and local Joule self-heating effects are essential elements to explain the abrupt drop in the electric field. In addition, the hysteresis behavior recorded during the I-V measurements shows strong dependence on delay time, i.e., the time needed for the polarization phenomena to occur.

Liquid crystal elastomers are currently of great interest due to their large thermally stimulated changes in shape. Here the authors show that by using an existing network and conducting carbon nanoparticles dispersed in a solvent with high swelling capability, a surface integrated layer can be created. This layer allows the effective resistivity to be reduced from highly insulating to usable values for electrical actuation and withstands large changes in geometrical shape both in contraction and expansion. Utilizing a resistive “Joule” heating effect, the reprocessed system shows a 150% length change and can be cycled beyond 10kcycles.

The authors find a simple analytic expression for the temperature of Joule heated nanowire by current pulse, which is important in the study of the current induced domain wall motion. Since the effect of spin transfer torque depends on the thermal energy of the system, the temperature of the nanowire is a vital information. Even though the numerical solution of the heat conduction equation is well established, not only does it require a lot of numerical effort, but neither does it give any physical insight. With appropriate assumptions and Green’s function method, the author derive a simple expression for the temperature of the nanowire as a function of the current density, sample geometry, and thermal properties of the substrate. The authors confirm the validity of their analytic expression by the comparison between the results of a simple expression and a commercial finite element method.

A comprehensive study of the mechanisms of heating and cooling originated by an electrical current in semiconductor devices is reported. The authors studied the Peltier, Joule, and Thomson phenomena self-consistently and found that the magnitudes of all of them were commensurable. A new formulation and interpretation of the Thomson effect are offered. The main conclusion of the present work is that the thermal analysis of any semiconductor device under real working conditions demands the inclusion of all heating and cooling mechanisms simultaneously.

The magnetotransport properties of La0.7Sr0.3MnO3 films were investigated in the nonlinear regime of strong Joule self-heating. In this regime the resistance-current characteristics exhibit two sharp transitions between bistable resistance values. The critical currents corresponding to the transitions depend on base temperature, magnetic field, current sweep rate, film resistance, and thermal coupling to the surroundings. This phenomenon opens up the possibility for the development of a magnetoresistance sensor based on Joule self-heating tuned colossal magnetoresistance.

We have used an in‐cavity hot CO2 cell to convert a conventional transversely excited atmospheric (TEA) CO2 laser to operation on the 00 °2 sequence transitions. Careful cavity design enables us to attain efficient energy extraction. Output energies of 6 J per pulse have been obtained from a nonselective cavity, while a grating‐tuned cavity produces numerous sequence lines having output energies in excess of 2 J per pulse.

Joule displacement microscopy, where the periodic expansion caused by Joule heating in a thin‐film track carrying ac current is mapped using a focused probe, has recently been described. In this letter, we demonstrate the application of this technique to the study of current distribution within a bipolar inverting gate.

Magnetic broadening of the iodine lasing line was found to increase the energy storage capability of the laser and thus increase the energy obtainable in a Q‐switched pulse from a few millijoules to a few tenths of a joule.