Viscoelastic effect and creep elimination of dielectric elastomers in adversarial resonance
Dielectricelastomers are known to exhibitviscoelasticproperties. When they are used in an adversarial resonator structure (known as a DEAR), the performance obtained is time-dependent. A thermodynamic model, involving the rheological model, is established to investigate the effect ofviscoelasticity on the dynamic response. We verified the validity of our model by comparing with the experimental results. Based on the model, we theoretically analyze how theviscoelasticity is affected by the peak voltage, frequency, pre-stretching, temperature, and the shape of the signal waveform. The equilibrium position of the deformed mem...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: Lei Liu, Bo Li, Wenjie Sun, Hualing Chen and Dichen Li Source Type: research
Analysis of quantum efficiency improvement in spin-polarized photocathode
GaAs/GaAsP strain-compensatedsuperlattices(SLs) were developed for spin-polarizedphotocathode applications. High crystal quality was maintained with SL thicknesses up to 720 nm (90-pairs); however, the quantum efficiency (QE) did not increase linearly with the SL thickness but became saturated starting from an SL thickness of 192 nm (24-pairs). Time-resolvedphotoluminescencemeasurements revealed that thecarrier lifetime in the GaAs/GaAsP strain-compensated SL was as short as 20.5 ps at room temperature, which causes the elimination of photoexcited electrons before emission. A simulation based on adiffusion model was i...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: Xiuguang Jin, Shunsuke Ohki, Tomoki Ishikawa, Atsushi Tackeuchi and Yosuke Honda Source Type: research
Isolated pentagons induced enhancement of conductance in ultra-narrow armchair graphene nanoribbon junctions
Recently, the narrowest armchairgraphene nanoribbon (AGNR) in the family of widthn = 3p + 2 has been fabricated [Kimoucheet al., Nat. Commun.6, 10177 (2015)]. Here, the effects of isolated pentagonal structures that are identified as the contacts of the formed AGNRs bymonomers have been investigated. Our first principles results show that the coupling of pentagons dominates thetransport properties of the junctions, i.e., a weak coupling enhances the conductance, remarkably higher than that of a perfect AGNR, whereas a strong coupling is opposite and the threshold voltage is not affected at all. Such a contrastive c...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: Xiang-Hua Zhang, Xiao-Fei Li and Qi Qiu Source Type: research
The low-loss EELS spectra from radiation damaged gold nanoparticles
The advantage of theEELS spectra intransmission electron microscopy is the ability to obtain plasmon information of the structure of individualnanoparticles. TheEELS analyses of the plasmonic information ofgoldnanoparticles were obtained before and after irradiation by theconvergent beam electron diffraction(CBED) technique. The results indicate that before irradiating thegoldnanoparticles (35 nm in diameter) by theCBED technique, only theEELS spectrum ofcarbon is obtained. Nevertheless, theEELS spectra ofgold were obtained afterCBED irradiation of thenanoparticles. The spectrum ofgold shows five plasmonic modes at 15.9...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: S. Tehuacanero-Cuapa, J. Reyes-Gasga, A. Rodr íguez-Gómez, D. Bahena, I. Hernández-Calderón and R. García-García Source Type: research
Localization and interaction effects of epitaxial Bi2Se3 bulk states in two-dimensional limit
Quantum interferenceeffects and electron-electron interactions are found to play an important role in two-dimensional (2D) bulk transport of topological insulator (TI)thin films, which were previously considered as 2D electron gas (2DEG) and explained on basis of Hikami-Larkin-Nagaoka formula and Lee-Ramakrishnantheory. The distinct massive Dirac-typeband structure of the TI bulk state gives rise to quantum corrections toconductivity due to interference and interactioneffects, which are quite different from that of a 2DEG. We interpret the experimental findings employing Lu-Shentheory particularly derived for the TI system...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: Rik Dey, Anupam Roy, Tanmoy Pramanik, Samaresh Guchhait, Sushant Sonde, Amritesh Rai, Leonard F. Register and Sanjay K. Banerjee Source Type: research
Study of field-induced chain conformation transformation in poly(L-lactic acid) based piezoelectric film by infrared spectroscopy
In this investigation, the chain conformation transformation of thepiezoelectricpolymer of a poly(L-Lactic Acid) (PLLA)film was analyzed under anelectric field for the first time using infrared spectroscopy. It is revealed that thepiezoelectric shear mode coefficient d14 ( ∼10 pC/N) of a stretchedα form PLLAfilm mainly comes from the rotation of C O dipoles inside thepolymer main chain. The reorientation of the dipoles causes the deformation of thecrystal structure, which corresponds to a shear mode strain macroscopically in the PLLAfilm along a 45 ° direction to thepolymer length. The back-bone of the molecul...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: Xinyu Du, Chunlin Zhao, Jinxi Zhang and Kailiang Ren Source Type: research
A high power impulse magnetron sputtering model to explain high deposition rate magnetic field configurations
High Power ImpulseMagnetronSputtering (HiPIMS) is one of the recent developments in the field ofmagnetronsputtering technology that is capable of producing high performance, high qualitythin films. Commercial implementation of HiPIMS technology has been a huge challenge due to its lowerdeposition rates compared to direct currentMagnetronSputtering. The cylindrically symmetric “TriPack”magnet pack for a 10 cm sputtermagnetron that was developed at the Center for Plasma Material Interactions was able to produce higherdeposition rates in HiPIMS compared to conventional pack HiPIMS for the same average power. The “Tri...
Source: Journal of Applied Physics - October 24, 2016 Category: Physics Authors: Priya Raman, Justin Weberski, Matthew Cheng, Ivan Shchelkanov and David N. Ruzic Source Type: research
Sensitivity study of multilayer thin-film bulk acoustic resonator for mass sensor application
The sensitivity ofmultilayer thin-film bulk acoustic resonators (MTFBARs) used as mass sensors is investigated. MTFBAR sensors with the structure of a mass-sensitive layer/electrode layer/piezo layer/electrode layer were used. Two methods, one usingelectric impedance and the other displacement, were adopted for the determination of sensitivity. Simulation results show that the two methods agree well, and thecharacteristicacoustic impedance and thickness of the non-piezo layers strongly affect mass sensitivity. It was found that highacoustic impedance in the non-piezo layer is not helpful for sensitivity improvement. Sensit...
Source: Journal of Applied Physics - October 21, 2016 Category: Physics Authors: Haiqiang Liu, Fang Li, Lifeng Qin and Qing-Ming Wang Source Type: research
Nonlinear standing wave and acoustic streaming in an exponential-shape resonator by gas-kinetic scheme simulation
Nonlinear standingwaves andacoustic streaming in an axial-symmetricalresonator with exponentially varying cross-sectional area were studied. A two-dimensional gas-kinetic Bhatnagar-Gross-Krook scheme based on the non-structure triangular grid was established to simulate nonlinear acoustic oscillations in theresonator. Details of the transient and steadyflow fields and streaming were developed. Theeffects of winding index of the exponential-shaperesonator, the displacement amplitude of the acoustic piston on the streaming, and thevortex pattern wereanalyzed. The results demonstrate that theacoustic streaming pattern in such...
Source: Journal of Applied Physics - October 21, 2016 Category: Physics Authors: Xiaoqing Zhang, Heying Feng and Chengwu Qu Source Type: research
Experimental realization of Talbot array illumination for a 2-dimensional phase grating
We present the result of a multiple phase level Talbot array illuminator (TAI) based on two dimensional phasegrating. Thegrating was fabricated on glass by a Deep Reactive IonEtching (DRIE) system with optimized gas combination recipe. The opening ratio of thegrating is ∼0.71 with a phase step of 11π. The experimental study on Talbot arrayilluminations (TAI's) of this fabricated device in near-field region was carried out using a He-Ne laser. The TAI's were observed at the positions 2.81 mm, 8.59 mm, 14.28 mm, and 20.57 mm along the light propagation direction. The computer simulations of wave field distributio...
Source: Journal of Applied Physics - October 21, 2016 Category: Physics Authors: Puspen Mondal, Mukund Kumar, Pragya Tiwari, A. K. Srivastava, J. A. Chakera and P. A. Naik Source Type: research
Corrugated Si nanowires with reduced thermal conductivity for wide-temperature-range thermoelectricity
We fabricated suspended straight and corrugated Sinanowires (NWs) from 55 nm thick Si-on-insulator and studied theirthermal conductivity using Raman mapping. We demonstrate that corrugations induce 60% –70% reduction in NWthermal conductivity at temperatures 300 –400 K. This proves the significance ofballistic phonontransport at these temperatures in sufficiently thin Si NWs and the efficiency of corrugations inthermal conductivity reduction for application inthermoelectricity. The experimental results presented here are in agreement with our NW thermalconductance calculation taking into account theeffect of corru...
Source: Journal of Applied Physics - October 21, 2016 Category: Physics Authors: Vladimir Poborchii, Yukinori Morita, Junichi Hattori, Tetsuya Tada and Pavel I. Geshev Source Type: research
Basic noise mechanisms of heat-assisted-magnetic recording
Heat-assisted magnetic recording (HAMR) is expected to be a key technology to significantly increase the areal storage density ofmagnetic recording devices. At high temperatures, thermally inducednoise becomes a major problem, which must be overcome in order to reliably write magnetic bits with narrowtransitions. We propose an elementary model based on the effective recording time window (ERTW) to compute the switching probability of bits during HAMR. With few assumptions, this analytical model allows to gain deeper insights into basicnoise mechanisms, likeAC and DCnoise. Finally, we discuss strategies to reducenoise and t...
Source: Journal of Applied Physics - October 21, 2016 Category: Physics Authors: Christoph Vogler, Claas Abert, Florian Bruckner, Dieter Suess and Dirk Praetorius Source Type: research
Breakdown dynamics of electrically exploding thin metal wires in vacuum
Using a two-frame intensified charge coupled device (iCCD) imaging system with a 2 ns exposure time, we observed the dynamics of voltage breakdown and corona generation in experiments of fast ns-time exploding fineNi and stainless-steel (SS)wires in a vacuum. These experiments show that corona generation along thewire surface is subjected to temporal-spatial inhomogeneity. For both metalwires, we observed an initial generation of a brightcathode spot before theionization of the entirewire length. Thiscathode spot does not expand with time. For 25.4 μm diameterNi and SSwireexplosions with positive polarity, breakdown...
Source: Journal of Applied Physics - October 20, 2016 Category: Physics Authors: G. S. Sarkisov, J. Caplinger, F. Parada and V. I. Sotnikov Source Type: research
Efficiency at maximum power for an Otto engine with ideal feedback
We propose an Otto heat engine that undergoes processes involving a special class of feedback and analyze theoretically its response. We use stochasticthermodynamics to determine the performancecharacteristics of the heat engine and indicate the possibility that its maximum efficiency can surpass the Carnot value. The analytical expression for efficiency at maximum power, including the effects resulting from feedback, reduces to that previously derived based on an engine without feedback. (Source: Journal of Applied Physics)
Source: Journal of Applied Physics - October 20, 2016 Category: Physics Authors: Honghui Wang, Jizhou He, Jianhui Wang and Zhaoqi Wu Source Type: research
Microstructure and intrinsic stress evolution during epitaxial film growth of an Ag0.93Al0.07 solid solution on Si(111); excessive planar faulting due to quantum confinement
The correlation of microstructural development and the kinetics offilm growth has been investigated during theepitaxialfilm growth of an ultrathinbinaryAg0.93Al0.07 solid solution on a Si(111)-7 ×7 surface at 300 K by the combination of high-resolution transmission electron microscopy,X-ray diffraction, scanning tunneling microscopy,low energy electron diffraction, and real-timein-situ stress measurements. Up to afilm thickness of 6 ± 2 nm,epitaxialAg0.93Al0.07film growth is characterized by the strikingly extensive formation of planar faults parallel to the film/substrate interface, while at larger thickness th...
Source: Journal of Applied Physics - October 20, 2016 Category: Physics Authors: D. Fl ötotto, Z. M. Wang, I. J. Markel, S. J. B. Kurz and E. J. Mittemeijer Source Type: research
