Developing passive MEMS DC/AC current sensor applicable to two-wire appliances with high measurement accuracy
A passiveMEMS DC/ACcurrentsensor with highmeasurement accuracy, accomplished by the methodology combining both the “stress-equilibrium” solution and the “position-free” solution, was proposed formeasuring electricity consumption of household equipment and Information and Communication Technology devices. For the “stress-equilibrium” solution, slots between two adjacent piezoelectric plates are implemented to minimize the distribution difference of the uneven stress close to the fixed end. Themeasurement error caused by the uneven stress distribution is decreased from 9% to 4% for ten-piezoelectric-plates and fr...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Dong F. Wang, Xiaodong Li, Weikang Xian, Huan Liu and Xin Liu Source Type: research
Graphene tunnel junctions with aluminum oxide barrier
We report a development ofgraphenetunnel junctions made bychemical vapor deposition growngraphene andsputteredaluminum insulating by anin-situ grownaluminum oxide. The thin oxide layer formed in between the metal layer and the two-dimensional material is a crucial part of atunnel junction. We characterized surface morphology of oxide layers and studiedtunneling spectra oflead andsilvertunnel junctions to estimate the quality of thealuminum oxide. The Brinkman-Rowell-Dynes model was applied to fit the conductance-voltage plots to calculate the thickness of oxide layers. Junctions withgraphene both on bottom and on top were ...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Ying Feng, Daniel J. Trainer and Ke Chen Source Type: research
Single-dot spectroscopy of boron and phosphorus codoped silicon quantum dots
Boron (B) and phosphorous (P)codoped siliconquantum dots (SiQDs) are dispersible in polar solvents without organic ligands, and exhibit size controllablephotoluminescence(PL) from 0.85 to 1.85 eV due to the electronic transitions between the donor and the acceptor states. We study thePL spectra of thecodoped SiQDs at roomtemperature and at 77 K. We show that the broadPL band ofcodopedcolloidal SiQDs (full width at half maximum is over 400 meV) is composed of narrowerPL bands of individualQDs with differentPL energies. We also show that thePLlinewidth of individualcodoped SiQDs is almost twice as large as those of undoped S...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Takashi Kanno, Hiroshi Sugimoto, Anna Fucikova, Jan Valenta and Minoru Fujii Source Type: research
Observation of charge transport through CdSe/ZnS quantum dots in a single-electron transistor structure
We fabricated single-electron transistors (SETs) having CdSe/ZnS core-shell-typequantum dots (CdSe/ZnS-QDs) as a Coulomb island using a wet chemistry technique. The CdSe/ZnS-QDs were deposited ontoAuelectrodes with or without the assistance of aself-assembled monolayer of octane(di)thiols. The CdSe/ZnS-QDs were adsorbed onto theAuelectrodes even without the interlayer of thiol molecules depending on the concentration of the CdSe/ZnS-QD solution. The electron-transportcharacteristics through the CdSe/ZnS-QDs were examined in an SET structure at 13 K.Coulomb blockade behavior with typical gate voltage dependence was clear...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Masanori Kobo, Makoto Yamamoto, Hisao Ishii and Yutaka Noguchi Source Type: research
Magnetic interactions in anisotropic Nd-Dy-Fe-Co-B/ α-Fe multilayer magnets
The magnetic properties and the possible interaction mechanisms ofanisotropic soft- and hard-magneticmultilayers have been investigated by altering the thickness of different kinds of spacer layers. The metalTa and the insulating oxides MgO, Cr2O3 have been chosen as spacer layers to investigate the characteristics of the interactions between soft- and hard-magnetic layers in theanisotropic Nd-Dy-Fe-Co-B/ α-Femultilayer system. The dipolar andexchange interaction between hard and soft phases are evaluated with the help of the first order reversal curve method. The onset of the nucleation field and the magnetization revers...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Z. M. Dai, W. Liu, X. T. Zhao, Z. Han, D. Kim, C. J. Choi and Z. D. Zhang Source Type: research
Low-temperature anomalous magnetic behavior of Co2TiO4 and Co2SnO4
We report the low-temperature anomalous magnetic behavior offerrimagnetic spinels cobalt orthotitanate (Co2TiO4), which exhibits magnetic compensation behavior across 31.74 K, and cobalt orthostannate (Co2SnO4) exhibiting two sequential magnetictransitions, namely (i)ferrimagnetic to paramagnetictransition with N éel temperature TN ∼ 41 K and reentrantspin-glass behavior with glasstransition temperature TSG ∼ 39 K. The Arrott plot (H/M versus M2) criterion has been used to extricate the order of sequential magnetictransitions occurring below TN. Negative slopes of the Arrott plots below 32 K, metamag...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: S. Nayak, K. Dasari, D. C. Joshi, P. Pramanik, R. Palai, A. Waske, R. N. Chauhan, N. Tiwari, T. Sarkar and S. Thota Source Type: research
Vortex dynamics in a thin superconducting film with a non-uniform magnetic field applied at its center with a small coil
This papermodels the dynamics ofvortices that are generated in the middle of a thin, large-area,superconducting film by a low-frequency magnetic field from a small coil, motivated by a desire to better understand measurements of thesuperconductingcoherence length made with a two-coil apparatus. When the applied field exceeds a critical value,vortices and antivortices originate near the middle of the film at the radius where theLorentz force of the screening supercurrent is largest. TheLorentz force from the screening supercurrent pushesvortices toward the center of the film and antivortices outward. In an experiment,vortic...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Thomas R. Lemberger and Yen Lee Loh Source Type: research
Perpendicular magnetic anisotropy of Co\Pt bilayers on ALD HfO2
PerpendicularMagnetic Anisotropy (PMA) is a key requirement for state of the art Magnetic Random Access Memories (MRAM). Currently, PMA has been widely reported in standard Magnetic Tunnel Junctionmaterial stacks using MgO as adielectric. In this contribution, we present the first report of PMA at the interface with a high-κdielectric grown by Atomic Layer Deposition, HfO2. The PMA appears afterannealing a HfO2\Co\Pt\Ru stack in N2 with the Keff of 0.25 mJ/m2 as determined by Vibrating Sample Magnetometry.X-Ray Diffraction andTransmission Electron Microscopy show that the appearance of PMA coincides withinterdiffusion and...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Bart F. Vermeulen, Jackson Wu, Johan Swerts, Sebastien Couet, Dimitri Linten, Iuliana P Radu, Kristiaan Temst, Geert Rampelberg, Christophe Detavernier, Guido Groeseneken and Koen Martens Source Type: research
Effective dielectric constants and spectral density analysis of plasmonic nanocomposites
Cermet or ceramic-metal composite coatings promise great potentials in light harvesting, but the complicated composite structure at the nanoscale induces a design challenge to predict their optical properties. We find that the effectivedielectric constants ofnanocomposites predicted by finite-difference-time-domain(FDTD) simulation results match those of different classicaleffective medium theories in their respective validity range. However, a precise prediction of thefabricatednanocompositeproperties for different filling factors is very challenging. In this work, we extract the spectral density functions in the Bergman ...
Source: Journal of Applied Physics - October 27, 2016 Category: Physics Authors: Jin You Lu, Aikifa Raza, Nicholas X. Fang, Gang Chen and TieJun Zhang Source Type: research
Zero bias anomaly in Andreev reflection spectroscopy
Zero bias anomalies have been observed inpoint contact Andreev reflection spectroscopy using conventionalsuperconductors, and they cannot be suppressed by a highlyspin-polarized current. By systematically varying the size of thepoint contact, the anomalies are found to be evolved from conductance dips outside thesuperconducting gap. These anomalies, which depend on the size of the interface, are not intrinsic to thesuperconductors but due to a largeresistance change when the contact region is driven to normal by an Oersted field. (Source: Journal of Applied Physics)
Source: Journal of Applied Physics - October 26, 2016 Category: Physics Authors: J. A. Gifford, G. J. Zhao, B. C. Li, J. Zhang, D. R. Kim and T. Y. Chen Source Type: research
Mechanical response of lithium fluoride under off-principal dynamic shock-ramp loading
Single crystallithium fluoride (LiF), oriented [100], was shock loaded and subsequently shocklessly compressed in twoexperiments at the Z Machine. Velocimetrymeasurements were employed to obtain an impactorvelocity, shock transit times, and in-situparticle velocities for LiF samples up to ∼1.8 mm thick. A dual thicknessLagrangiananalysis was performed on the in-situ velocimetry data to obtain the mechanical response along the loading path of theseexperiments. An elastic response was observed on oneexperiment during initial shockless compression from 100 GPa before yielding. The relatively large thickness differences...
Source: Journal of Applied Physics - October 26, 2016 Category: Physics Authors: Christopher T. Seagle, Jean-Paul Davis and Marcus D. Knudson Source Type: research
Mechanical and optical response of [100] lithium fluoride to multi-megabar dynamic pressures
We present a new model for therefractive index of LiF that includes temperature dependence and describe a procedure for correcting apparentvelocity to truevelocity for dynamic compressionexperiments. (Source: Journal of Applied Physics)
Source: Journal of Applied Physics - October 26, 2016 Category: Physics Authors: Jean-Paul Davis, Marcus D. Knudson, Luke Shulenburger and Scott D. Crockett Source Type: research
Elastic constants of polycrystals with generally anisotropic crystals
A homogenization model is developed that describes the effective elastic constants ofpolycrystallinematerials with constituent crystallites of generalanisotropy (triclinic symmetry). The model is solved through an iterative technique where successive iterations improve the estimates of the polycrystal's elastic constants. Convergence of the solution provides the self-consistent elastic constants, which are the polycrystal's elastic constants resulting from continuity between local and far-fieldstress and strains. Iterative solutions prior to convergence are the bounds on the elastic constants including the Voigt-Reuss and ...
Source: Journal of Applied Physics - October 26, 2016 Category: Physics Authors: Christopher M. Kube and Maarten de Jong Source Type: research
First-principles study of the defected phosphorene under tensile strain
By using first-principles calculations, we investigate the defected phosphorene withvacancies under tensile conditions, specifically focusing on itsstress-strain relation,band gap, and Lidiffusion through the doublevacancy. The analysis of thestress-strain relation indicates that, owing to the presence ofvacancies, the mechanical properties of phosphorene are significantly degraded in the zigzag direction, including the ideal strength andYoung's modulus. Moreover, it is found that tensile strain produces a remarkable reduction in theband gap of the defected phosphorene, and Lidiffusion through the defected phosphorene is m...
Source: Journal of Applied Physics - October 26, 2016 Category: Physics Authors: Feng Hao and Xi Chen Source Type: research
Carbon nanotube —Based cold cathodes: Field emission angular properties and temporal stability
Thefield emission (FE)properties ofcarbon nanotube (CNT)-basedcathodes have been investigated on nanostructured surfaces grown by plasma enhanced chemical vapor deposition. The FE angularproperties and temporal stability of the emergentelectron beam have been determined using a dedicated apparatus forcathodes of various architectures and geometries, characterized byscanning electron microscopy and I –V measurements. The angularelectron beam divergence and time instability at the extraction stage, which are crucial parameters in order to obtain high brilliance of FE-based-cathodeelectron sources, have been measured for el...
Source: Journal of Applied Physics - October 26, 2016 Category: Physics Authors: S. Iacobucci, M. Fratini, A. Rizzo, Y. Zhang, M. T. Cole, W. I. Milne, S. Lagomarsino, A. Liscio and G. Stefani Source Type: research
