Multiferroic cantilever for power generation using dual functionality
Lead zirconate titanate (PZT)/Ni cantilevers have been developed using the pulsed laser deposition technique for harnessing magnetic as well asmechanical energy. High voltage (1.2 mV, 1.8 mV, and 8.5 mV) and power density (1100, 2400, and 3600 mW/m3) were generated across the PZT/Ni cantilevers (in 3 –3 mode) havingPZT thin films deposited at 100 mTorr, 200 mTorr, and 300 mTorr oxygen pressures, respectively, at their respective resonance frequencies with 0.5 g acceleration. Maximum power response (3600 mW/m3) was observed at a load resistance of 100 kΩ for the cantilever havingPZT film deposited at 300 mTo...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Reema Gupta, Monika Tomar, S. Rammohan, R. S. Katiyar and Vinay Gupta Source Type: research
Electronic properties of monolayer tungsten disulfide grown by chemical vapor deposition
We demonstratechemical vapor deposition of largemonolayer tungsten disulfide (WS2) (>200 μm).Photoluminescence and Raman spectroscopy provide insight into the structural and strain heterogeneity of the flakes. We observe exciton quenching at grain boundaries that originate from the nucleation site at the center of the WS2 flakes.Temperature variable transportmeasurements of top-gated WS2transistors show an apparent metal-to-insulator transition. Variable range and thermally activated hopping mechanisms can explain the carrier transport in the insulating phase at low and intermediatetemperatures. The devices exhibit roo...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Abdullah Alharbi and Davood Shahrjerdi Source Type: research
Observation of three-mode parametric instability in a micromechanical resonator
We present systematic experimental observations of three-mode auto-parametric instability in a micromechanicalresonator analogous to previous experimental observations of this effect in optical parametricresonators. The three-mode instability is triggered when a driven mode at frequencyωd couples to two lower frequency modes (frequenciesω1 andω2) such thatωd = ω1 + ω2. Similar to the 2 mode instability, the phenomenon is seen to be threshold dependent and sensitive to driving conditions and system parameters. In support of the experimental observations, a dynamical model has also been specified. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Adarsh Ganesan, Cuong Do and Ashwin Seshia Source Type: research
Lower limits of line resistance in nanocrystalline back end of line Cu interconnects
The strong non-linear increase in theCuinterconnect lineresistance with decreasing linewidth presents a significant obstacle to their continued downscaling. In this letter we use the first principlesdensity functional theory based electronic structure ofCuinterconnects to find the lower limits of their lineresistance for metal linewidths corresponding to future technology nodes. We find that even in the absence of scattering due tograin boundaries, edge roughness or interfaces, quantum confinement causes a severe increase in the lineresistance ofCu. We also find that when the simplest scattering mechanism in thegrain bound...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Ganesh Hegde, R. Chris Bowen and Mark S. Rodder Source Type: research
Color center fluorescence and spin manipulation in single crystal, pyramidal diamond tips
We investigate bright fluorescence of nitrogen (NV)- and silicon-vacancycolor centers in pyramidal,single crystaldiamond tips, which are commercially available as atomic force microscope probes. We coherently manipulate NV electronic spin ensembles withT2 = 7.7(3) μs.Color center lifetimes in different tip heights indicate effective refractive index effects and quenching. Using numerical simulations, we verify enhanced photon rates from emitters close to thepyramid apex rendering them promising as scanning probesensors. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Richard Nelz, Philipp Fuchs, Oliver Opaluch, Selda Sonusen, Natalia Savenko, Vitali Podgursky and Elke Neu Source Type: research
Observation of Mg-induced structural and electronic properties of graphene
We report the formation of superstructures induced byMg adatoms on a single layergraphene (SLG) formed on Ni(111) substrate, where a strong metallic parabolic band is found near the Fermi level at the Γ-point of the Brillouin zone. Our valence band and core level data obtained by using synchrotron photons indicate thatMg adatoms intercalate initially to lift the SLG from theNi substrate to produce a well-defined π-band of SLG, and then the parabolic band appears upon adding extraMg atoms on the Mg-intercalated SLG. Ourscanning tunneling microscopy images from these systems show the presence of superstructures, a 2 √3...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Heemin Park, Laishram Tomba Singh, Paengro Lee, Jingul Kim, Mintae Ryu, Chan-Cuk Hwang, Kwang S. Kim and Jinwook Chung Source Type: research
Growth of continuous graphene by open roll-to-roll chemical vapor deposition
We demonstrate the growth of high-quality, continuousmonolayergraphene onCu foils using an open roll-to-roll (R2R) chemical vapor deposition(CVD) reactor with both static and moving foil growth conditions. N2 instead of Ar was used as carrier gas to reduce process cost, and the concentrations of H2 and CH4 reactants were kept below the lower explosive limit to ensure process safety for reactor ends open to ambient. Thecarrier mobility ofgraphene deposited at aCu foil winding speed of 5 mm/min was 5270–6040 cm2 V−1 s−1 at room temperature (on 50 μm × 50 μm Hall devices). These results will enabl...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Guofang Zhong, Xingyi Wu, Lorenzo D'Arsie, Kenneth B. K. Teo, Nalin L. Rupesinghe, Alex Jouvray and John Robertson Source Type: research
Strain measurement in ferromagnetic crystals using dark-field electron holography
This study proposes a method to separate thegeometric phase shift due to lattice strain from the undesired phase information, resulting frommagnetic fields that are superposed in the dark-fieldelectron holography (DFEH) observations. Choosing a distinct wave vector for the Bragg reflection reversed the sense of thegeometric phase shift, while the sense of the magnetic information remained unchanged. In the case of an Nd-Fe-B permanent magnet, once the unwanted signal was removed by data processing, the residual phaseimage revealed a strain map. Even though the applications of DFEH have thus far been limited tonon-magnetic ...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Yasukazu Murakami, Kodai Niitsu, Syuhei Kaneko, Toshiaki Tanigaki, Taisuke Sasaki, Zentaro Akase, Daisuke Shindo, Tadakatsu Ohkubo and Kazuhiro Hono Source Type: research
Enhanced tunneling electroresistance in multiferroic tunnel junctions due to the reversible modulation of orbitals overlap
We report a first-principles study of theferroelectricity and spin-dependent transport through Co/BaTiO3/CoO/Co multiferroictunnel junctions (MFTJs). We find the coexistence of largetunneling magnetoresistance(TMR) ratio and largetunneling electroresistance (TER) ratio in the MFTJs. The largeTMReffect originates from the spin-filtertunneling through the BaTiO3 barrier, while the TEReffect is due to the modulation of orbitals overlap bypolarization reversal. The microscopic physics of TER are identified and understood through the analysis of metal-oxygen relative displacements, localpolarization magnitude, transmission in m...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Leina Jiang, L. L. Tao, B. S. Yang, J. Wang and X. F. Han Source Type: research
Giant piezoelectric response in piezoelectric/dielectric superlattices due to flexoelectric effect
Flexoelectricity describes the linear response of electricalpolarization to a strain gradient, which can be used to enhance thepiezoelectric effect ofpiezoelectric material or realize thepiezoelectric effect in nonpiezoelectric materials. Here, we demonstrate from thermodynamics theory that a giantpiezoelectric effect exists in piezoelectric/dielectricsuperlattices due toflexoelectric effect. The apparentpiezoelectric coefficient is calculated from the closed-form of analytical expression of thepolarization distribution in the piezoelectric/dielectricsuperlattice subjected to a normal stress, in which theflexoelectric effe...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Chang Liu, Huaping Wu and Jie Wang Source Type: research
Ionic liquid gating of ultra-thin YBa2Cu3O7 −x films
In this paper, we present a detailed investigation of the self-fieldtransport properties of anionic liquid gated ultra-thin YBa2Cu3O7 −x(YBCO)film. From the high temperature dynamic of theresistivity (>220 K), different scenarios pertaining to the interaction between theliquid and thethin film are proposed. From the low temperature evolution ofJc andTc, a comparison between the behavior of our system and the standard properties ofYBCO is drawn. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: A. F ête, L. Rossi, A. Augieri and C. Senatore Source Type: research
Pt thickness dependence of spin Hall effect switching of in-plane magnetized CoFeB free layers studied by differential planar Hall effect
We introduce a differential planar Halleffect method that enables the experimental study of spin orbittorque switching of in-plane magnetized free layers in a simpleHall bar device geometry. Using this method, we study the Pt thickness dependence of switchingcurrents and show that they decrease monotonically down to the minimum experimental thickness of ∼5 nm, while thecritical current and power densities are very weakly thickness dependent, exhibiting the minimum values ofJc0 = 1.1 × 108 A/cm2 andρJc02=0.6×1012 W/cm3 at this minimum thickness. Our results suggest that a significant reduction of the cri...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: G. Mihajlovi ć, O. Mosendz, L. Wan, N. Smith, Y. Choi, Y. Wang and J. A. Katine Source Type: research
Theoretical study of microwave-assisted magnetization switching in exchange coupled nano magnets
Microwave-assistedmagnetization switching (MAS) in an exchange-coupled-composite (ECC) nano-magnet wasanalyzed based on the macrospin-model. The ECC nano-magnet consists of the perpendicularlymagnetized soft and hardmagnetic layers which areferromagnetically coupled with each other through the interlayer exchange coupling,χ. With increasingχ a reentrant transition from the MAS-non-effective state to the MAS-effective state appears. There exists a region ofχ where the switching field is reduced by application of themicrowave field. The width of this MAS-effective region ofχ decreases with an increase of the frequency of...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: T. Yamaji and H. Imamura Source Type: research
Field-angle and DC-bias dependence of spin-torque diode in giant magnetoresistive microstripe
The spintorque diode effect in all metal spintronic devices has been proposed as amicrowave detector with a high power limit and resistivity to breakdown. The previous works have revealed the field-angle dependence of the rectified DC voltage (VDC) in theferromagnetic stripe. The giantmagnetoresistive(GMR) microstripe exhibits higher sensitivity compared with theferromagnetic stripe. However, the influence of themagnetic field direction and bias current in the spinrectification ofGMR microstripe is not yet reported. In this work, the angular dependence and bias dependence of resonant frequency (fR) andVDC are investigated....
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: X. Li, Y. Zhou, C. Zheng, P. H. Chan, M. Chan and Philip W. T. Pong Source Type: research
Electrical detection of magnetic domain walls by inverse and direct spin Hall effect
Domain wall (DW) detection is a prerequisite to perform current-induced DW motion. In this letter, we demonstrate a detection method, based on the ability for aferromagneticnanowire, in which a DW is pinned, to inject or detect a pure spincurrent. The device consists of such aferromagneticnanowire in contact with an orthogonal spin Hall effect (SHE)nanowire. When acurrent flows along theferromagneticnanowire, and provided a DW is pinned, the pure spincurrent is transformed into a transverse voltage byinverse spin Hall effect (ISHE). In the reciprocal configuration, the pure spincurrent created by the direct SHE, generates ...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: V. T. Pham, G. Zahnd, A. Marty, W. Savero Torres, M. Jamet, P. No ël, L. Vila and J. P. Attané Source Type: research
