Results for "Weisheng Zhao"

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A Scalable Pipelined Dataflow Accelerator for Object Region Proposals on FPGA PlatformOct 26 2018Region proposal is critical for object detection while it usually poses a bottleneck in improving the computation efficiency on traditional control-flow architectures. We have observed region proposal tasks are potentially suitable for performing pipelined ... More
Spin-Cherenkov effect in a magnetic nanostrip with interfacial Dzyaloshinskii-Moriya interactionJan 28 2016Apr 12 2016Spin-Cherenkov effect enables strong excitations of spin waves (SWs) with nonlinear wave dispersions. The Dzyaloshinskii-Moriya interaction (DMI) results in anisotropy and nonreciprocity of SWs propagation. In this work, we study the effect of the interfacial ... More
Magnetic skyrmion-based synaptic devicesAug 29 2016Magnetic skyrmions are promising candidates for next-generation information carriers, owing to their small size, topological stability, and ultralow depinning current density. A wide variety of skyrmionic device concepts and prototypes have been proposed, ... More
The Bondage Number of the Strong Product of a Complete Graph and a PathDec 28 2013The bondage number $b(G)$ of a graph $G$ is the cardinality of a minimum edge set whose removal from $G$ results in a graph with the domination number greater than that of $G$. It is a parameter to measure the vulnerability of a communication network ... More
Complementary Skyrmion Racetrack Memory with Voltage ManipulationFeb 29 2016Magnetic skyrmion holds promise as information carriers in the next-generation memory and logic devices, owing to the topological stability, small size and extremely low current needed to drive it. One of the most potential applications of skyrmion is ... More
Control and manipulation of a magnetic skyrmionium in nanostructuresApr 20 2016Sep 03 2016A magnetic skyrmionium is a nontopological soliton, which has a doughnut-like out-of-plane spin texture in thin films, and can be phenomenologically viewed as a coalition of two topological magnetic skyrmions with opposite topological numbers. Due to ... More
Spintronics based Stochastic Computing for Efficient Bayesian Inference SystemNov 03 2017Bayesian inference is an effective approach for solving statistical learning problems especially with uncertainty and incompleteness. However, inference efficiencies are physically limited by the bottlenecks of conventional computing platforms. In this ... More
Efficient technique for ab-initio calculation of magnetocrystalline anisotropy energyJun 05 2018Nov 01 2018Ab-initio calculation of magnetocrystalline anisotropy energy (MCAE) often requires a strict convergence criterion and a dense k-point mesh to sample the Brillouin zone, making its convergence problematic and time-consuming. The force theorem for MCAE ... More
Magnetoresistive sensors based on the elasticity of domain wallsJan 04 2018Magnetic sensors based on the magnetoresistance effects have a promising application prospect due to their excellent sensitivity and advantages in terms of the integration. However, competition between higher sensitivity and larger measuring range remains ... More
Are Yao Graph and Theta Graph Void Free?Feb 21 2013Jul 02 2013Greedy Forwarding algorithm is a widely-used routing algorithm for wireless networks. However, it can fail if network topologies (usually modeled by geometric graphs) contain voids. Since Yao Graph and Theta Graph are two types of geometric graphs exploited ... More
Dynamics of magnetic skyrmion clusters driven by spin-polarized current with a spatially varied polarizationJan 26 2018Apr 06 2018Magnetic skyrmions are promising candidates for future information technology. Here, we present a micromagnetic study of isolated skyrmions and skyrmion clusters in ferromagnetic nanodisks driven by the spin-polarized current with spatially varied polarization. ... More
Low spin-polarization in the heavy metal\ferromagnet structures detected through the domain wall motion by synchronized magnetic field and currentJan 26 2019CoFeB is a very soft material, in which Domain Wall (DW) can be moved easily under a weak magnetic field. However, it is very difficult to move DWs in Ta\CoFeB\MgO nanowires with interfacial perpendicular magnetic anisotropy through a spin-polarized current, ... More
Quasi-1D graphene superlattices formed on high index surfacesFeb 17 2014We report preparation of large area quasi-1D monolayer graphene superlattices on a prototypical high index surface Cu(410)-O and characterization by Raman spectroscopy, Auger electron spectroscopy (AES), low energy electron diffraction (LEED), scanning ... More
Magnetization reversal more rapidly by using an ultrashort square-wave laser pulseFeb 25 2019With the feature of low-power magnetization manipulation at an ultrashort time scale, all optical switching (AOS) has been propelled to the forefront in investigations. To further speed up the magnetization reversal by manipulating ultrashort optical ... More
Intelligent Identification of Two-Dimensional Structure by Machine-Learning Optical MicroscopyMar 06 2018Two-dimensional (2D) materials and their heterostructures, with wafer-scale synthesis methods and fascinating properties, have attracted numerous interest and triggered revolutions of corresponding device applications. However, facile methods to realize ... More
Skyrmions in magnetic tunnel junctionsMar 14 2018In this work, we demonstrate that skyrmions can be nucleated in the free layer of a magnetic tunnel junction (MTJ) with Dzyaloshinskii-Moriya interactions (DMI) by a spin-polarized current with the assistance of stray fields from the pinned layer. The ... More
ELM-Based Distributed Cooperative Learning Over NetworksApr 04 2015Nov 30 2015This paper investigates distributed cooperative learning algorithms for data processing in a network setting. Specifically, the extreme learning machine (ELM) is introduced to train a set of data distributed across several components, and each component ... More
Enhancement of Spintronic Terahertz Emission via Annealing in Ferromagnetic HeterostructuresDec 18 2018Feb 03 2019We systematically investigate the influence of annealing effect on terahertz (THz) generation from CoFeB based magnetic nanofilms driven by femtosecond laser pulses. Three times enhancement of THz yields are achieved in W/CoFeB through annealing effect, ... More
Intrinsic Spin Hall Conductivity of MoTe2 and WTe2 SemimetalsDec 17 2018We report a comprehensive study on the intrinsic spin Hall conductivity (SHC) of semimetals MoTe2 and WTe2 by ab initio calculation. Large SHC and desirable spin Hall angles have been discovered, due to the strong spin orbit coupling effect and low charge ... More
Magnetization dynamics driven by the Dzyaloshinskii-Moriya interaction in the double-interface spin transfer torque magnetic tunnel junctionMay 16 2019Currently double-interface MTJs have been developed for enhancing the thermal stability barrier in small technology node. Dzyaloshinskii-Moriya interaction (DMI) inevitably exists in such devices due to the use of the heavy-metal/ferromagnet structures. ... More
Calculation of intrinsic spin Hall conductivity by Wannier interpolationOct 17 2018\textit{Ab-initio} calculation of intrinsic spin Hall conductivity (SHC) generally requires a strict convergence criterion and a dense k-point mesh to sample the Brillouin zone, making its convergence challenging and time-consuming. Here we present a ... More
First-principles investigation of magnetocrystalline anisotropy oscillations in Co$_{2}$FeAl/Ta heterostructuresDec 06 2017Feb 09 2018We report first-principles investigations of magnetocrystalline anisotropy energy (MCAE) oscillations as a function of capping layer thickness in Heusler alloy Co\textsubscript{2}FeAl/Ta heterostructures. Substantial oscillation is observed in FeAl-interface ... More
eSLAM: An Energy-Efficient Accelerator for Real-Time ORB-SLAM on FPGA PlatformJun 03 2019Simultaneous Localization and Mapping (SLAM) is a critical task for autonomous navigation. However, due to the computational complexity of SLAM algorithms, it is very difficult to achieve real-time implementation on low-power platforms.We propose an energy ... More
AWG-based Non-blocking Clos NetworksAug 21 2013Sep 13 2014The three-stage Clos networks remain the most popular solution to many practical switching systems to date. The aim of this paper is to show that the modular structure of Clos networks is invariant with respect to the technological changes. Due to the ... More
Large tunneling magnetoresistance in VSe2/MoS2 magnetic tunnel junctionApr 16 2019Two-dimensional (2D) van der Waals (vdW) materials provide the possibility of realizing heterostructures with coveted properties. Here, we report a theoretical investigation of the vdW magnetic tunnel junction (MTJ) based on VSe2/MoS2 heterojunction, ... More
Tunneling magnetoresistance enhancement by symmetrization in spin-orbit torque magnetic tunnel junctionFeb 15 2018May 14 2018Heavy metals with strong spin-orbit coupling (SOC) have been employed to generate spin current to control the magnetization dynamics by spin-orbit torque (SOT). Magnetic tunnel junction based on SOT (SOT-MTJ) is a promising application with efficient ... More
SPINBIS: Spintronics based Bayesian Inference System with Stochastic ComputingFeb 19 2019Bayesian inference is an effective approach for solving statistical learning problems, especially with uncertainty and incompleteness. However, Bayesian inference is a computing-intensive task whose efficiency is physically limited by the bottlenecks ... More
Low-Power (1T1N) Skyrmionic Synapses for Spiking Neuromorphic SystemsNov 06 2018In this work, we propose a `1-transistor 1-nanotrack' (1T1N) synapse based on movement of magnetic skyrmions using spin polarised current pulses. The proposed synaptic bit-cell has 4 terminals and fully decoupled spike transmission- and programming- paths. ... More
Modified Schmidt games and non-dense forward orbits of partially hyperbolic systemsApr 08 2015Apr 11 2015Let $f: M \to M$ be a $C^{1+\theta}$-partially hyperbolic diffeomorphism. We introduce a type of modified Schmidt games which is induced by $f$ and played on any unstable manifold. Utilizing it we generalize some results of \cite{Wu} as follows. Consider ... More
Higher rank rigidity for Berwald spacesOct 15 2015Nov 07 2018We generalize the higher rank rigidity theorem to a class of Finsler spaces, i.e. Berwald spaces. More precisely, we prove that a complete connected Berwald space of finite volume and bounded nonpositive flag curvature with rank at least $2$ whose universal ... More
From Graph Isoperimetric Inequality to Network Connectivity -- A New ApproachJul 13 2016We present a new, novel approach to obtaining a network's connectivity. More specifically, we show that there exists a relationship between a network's graph isoperimetric properties and its conditional connectivity. A network's connectivity is the minimum ... More
Direct observation of domain wall surface tension by deflating or inflating a magnetic bubbleAug 22 2017The surface energy of a magnetic Domain Wall (DW) strongly affects its static and dynamic behaviours. However, this effect was seldom directly observed and many related phenomena have not been well understood. Moreover, a reliable method to quantify the ... More
Cross-point architecture for spin transfer torque magnetic random access memoryFeb 08 2012Spin transfer torque magnetic random access memory (STT-MRAM) is considered as one of the most promising candidates to build up a true universal memory thanks to its fast write/read speed, infinite endurance and non-volatility. However the conventional ... More
A microwave field-driven transistor-like skyrmionic device with the microwave current-assisted skyrmion creationJan 21 2016Oct 03 2017Magnetic skyrmion is a topologically protected domain-wall structure at nanoscale, which could serve as a basic building block for advanced spintronic devices. Here, we propose a microwave field-driven skyrmionic device with the transistor-like function, ... More
Magnetic skyrmion spectrum under voltage excitation and its non-linear modulationMar 31 2019Magnetic skyrmions are topological quasiparticles with great potential for applications in future information storage and processing devices because of their nanoscale size, high stability, and large velocity. Recently, the high-frequency properties of ... More
Dynamics of a magnetic skyrmionium driven by spin wavesFeb 12 2018Mar 23 2018The magnetic skyrmionium is a skyrmion-like structure but carries a zero net skyrmion number, which can be used as a building block for non-volatile information processing devices. Here, we study the dynamics of a magnetic skyrmionium driven by propagating ... More
Large phase-transition-induced magnetic anisotropy change in (Co/Pt)2/VO2 heterostructureSep 19 2018We report the phase-transition controlled magnetic anisotropy modulation in the (Co/Pt)2/VO2 heterostructure, where VO2 is introduced into the system to applied an interfacial strain by its metal-insulator transition. A large reversible modulation of ... More
Current-limiting challenges for all-spin logic devicesJun 12 2015Sep 23 2015All-spin logic device (ASLD) has attracted increasing interests as one of the most promising post-CMOS device candidates, thanks to its low power, non-volatility and logic-in-memory structure. Here we investigate the key current-limiting factors and develop ... More
Enhanced Interfacial Dzyaloshinskii-Moriya Interaction in annealed Pt/Co/MgO structuresFeb 08 2019The interfacial Dzyaloshinskii-Moriya interaction (iDMI) is attracting great interests for spintronics. An iDMI constant larger than 3 mJ/m^2 is expected to minimize the size of skyrmions and to optimize the DW dynamics. In this study, we experimentally ... More
Field-free spin-orbit-torque switching of perpendicular magnetization aided by uniaxial shape anisotropyMar 27 2019It has been demonstrated that the switching of perpendicular magnetization can be achieved with spin orbit torque (SOT) at an ultrafast speed and low energy consumption. However, to make the switching deterministic, an undesirable magnetic field or unconventional ... More
Exploiting Spin-Orbit Torque Devices as Reconfigurable Logic for Circuit ObfuscationFeb 08 2018Circuit obfuscation is a frequently used approach to conceal logic functionalities in order to prevent reverse engineering attacks on fabricated chips. Efficient obfuscation implementations are expected with lower design complexity and overhead but higher ... More
Skyrmions as Compact, Robust and Energy-Efficient Interconnects for Domain Wall (DW)-based SystemsJan 12 2016Magnetic domain-wall (DW) has been widely investigated for future memory and computing systems. However, energy efficiency and stability become two major challenges of DW-based systems. In this letter, we first propose exploiting skyrmions as on-chip ... More
Schmidt Games and Nondense forward Orbits of certain Partially Hyperbolic SystemsNov 21 2013Let $f: M \to M$ be a partially hyperbolic diffeomorphism with conformality on unstable manifolds. Consider a set of points with nondense forward orbit: $E(f, y) := \{ z\in M: y\notin \overline{\{f^k(z), k \in \mathbb{N}\}}\}$ for some $y \in M$. Define ... More
Higher rank rigidity for Berwald spacesOct 15 2015Oct 16 2015We generalize the higher rank rigidity theorem to a class of Finsler spaces, i.e. Berwald spaces. More precisely, we prove that a complete connected reversible Berwald space of finite volume and bounded nonpositive flag curvature with rank at least 2 ... More
On non-dense orbits of certain non-algebraic dynamical systemsJul 29 2015Dec 27 2015In this paper, we manage to apply Schmidt games to certain non-algebraic dynamical systems. More precisely, we show that the set of points with non-dense forward orbit under a $C^2$-Anosov diffeomorphism with conformality on unstable manifolds is a winning ... More
On the ergodicity of geodesic flows on surfaces of nonpositive curvatureSep 25 2013Mar 31 2015Let $M$ be a smooth compact surface of nonpositive curvature, with genus $\geq 2$. We prove the ergodicity of the geodesic flow on the unit tangent bundle of $M$ with respect to the Liouville measure under the condition that the set of points with negative ... More
Ultra-Fast Ferrimagnetic All Spin Logic DeviceMar 07 2018All spin logic device (ASLD) blazes an alternative path for realizing ultra-low power computing in the Post-Moore era. However, initial device structure relying on ferromagnetic input/output and spin transfer torque (STT) driven magnetization switching ... More
Perspectives of Racetrack Memory for Large-Capacity On-Chip Memory: From Device to SystemFeb 06 2016Current-induced domain wall motion (CIDWM) is regarded as a promising way towards achieving emerging high-density, high-speed and low-power non-volatile devices. Racetrack memory is an attractive spintronic memory based on this phenomenon, which can store ... More
A gate-variable spin current demultiplexer based on grapheneAug 17 2016Spintronics, which utilizes spin as information carrier, is a promising solution for nonvolatile memory and low-power computing in the post-Moore era. An important challenge is to realize long distance spin transport, together with efficient manipulation ... More
Tuning the Dzyaloshinskii-Moriya Interaction in Pt/Co/MgO heterostructures through MgO thicknessOct 25 2017Apr 02 2018The interfacial Dzyaloshinskii-Moriya interaction (DMI) in the ferromagnetic/heavy metal ultra-thin film structures , has attracted a lot of attention thanks to its capability to stabilize Neel-type domain walls (DWs) and magnetic skyrmions for the realization ... More
Energy-efficient domain wall motion governed by the interplay of helicity-dependent optical effect and spin-orbit torqueOct 12 2018Feb 12 2019Spin-orbit torque provides a powerful means of manipulating domain walls along magnetic wires. However, the current density required for domain wall motion is still too high to realize low power devices. Here we experimentally demonstrate helicity-dependent ... More
Voltage Controlled Magnetic Skyrmion Motion for Racetrack MemoryJul 29 2015Feb 26 2016Magnetic skyrmion, vortex-like swirling topologically stable spin configurations, is appealing as information carrier for future nanoelectronics, owing to the stability, small size and extremely low driving current density. One of the most promising applications ... More
Voltage-Driven High-Speed Skyrmion Motion in a Skyrmion Shift DeviceMar 15 2018Magnetic skyrmions are promising information carriers for building future high-density and high-speed spintronic devices. However, to achieve a current-driven high-speed skyrmion motion, the required driving current density is usually very large, which ... More
Universal domain wall dynamics under electric field in Ta/CoFeB/MgO devices with perpendicular anisotropyNov 19 2014Jun 28 2016Electric field effects in ferromagnetic/oxide dielectric structures provide a new route to control domain wall (DW) dynamics with low power dissipation. However, electric field effects on DW velocities have only been observed so far in the creep regime ... More
A decade of skyrmionics: Writing, deleting, reading and processing magnetic skyrmions roward spintronic applicationsJun 11 2019The field of skyrmionics has been actively investigated across a wide range of topics during the last decade. In this topical review, we review and discuss key results and findings in skyrmionics since the first experimental observation of magnetic skyrmions ... More
Magnetic skyrmion transistor operated with microwavesJan 21 2016Aug 20 2016Magnetic skyrmion is a topologically protected magnetic domain-wall structure at nanoscale, which might be a basic building block for advanced spintronic devices. Here, we propose the microwave-driven motion of a magnetic skyrmion in a voltage-gated nanotrack, ... More
Amplicification of Voltage Controlled Magnetic Anisotropy Effect with Negative CapacitanceOct 31 2016The high current density required by Magnetic Tunneling Junction (MTJ) switching driven by Spin Transfer Torque (STT) effect leads to large power consumption and severe reliability issues therefore hinder the timetable for STT Magnetic Random Access Memory ... More
Dynamics of magnetic skyrmion clusters driven by spin-polarized current with a spatially varied polarizationJan 26 2018Feb 03 2018Magnetic skyrmions are promising candidates for future information technology. Here, we present a micromagnetic study of isolated skyrmions and skyrmion clusters in a ferromagnetic nanodisk driven by the spin-polarized current with spatially varied polarization. ... More
Influence of heavy metal materials on magnetic properties of Pt/Co/heavy metal tri-layered structuresSep 23 2016Pt/Co/heavy metal (HM) tri-layered structures with interfacial perpendicular magnetic anisotropy (PMA) are currently under intensive research for several emerging spintronics effects, such as spin-orbit torque (SOT), domain wall motion, and room temperature ... More
Influence of heavy metal materials on magnetic properties of Pt/Co/heavy metal tri-layered structuresSep 23 2016Mar 01 2017Pt/Co/heavy metal (HM) tri-layered structures with interfacial perpendicular magnetic anisotropy (PMA) are currently under intensive research for several emerging spintronic effects, such as spinorbit torque, domain wall motion, and room temperature skyrmions. ... More
A decade of skyrmionics: Writing, deleting, reading and processing magnetic skyrmions toward spintronic applicationsJun 11 2019Jun 12 2019The field of skyrmionics has been actively investigated across a wide range of topics during the last decade. In this topical review, we review and discuss key results and findings in skyrmionics since the first experimental observation of magnetic skyrmions ... More
Application of Machine Learning in Fiber Nonlinearity Modeling and Monitoring for Elastic Optical NetworksNov 23 2018May 23 2019Fiber nonlinear interference (NLI) modeling and monitoring are the key building blocks to support elastic optical networks (EONs). In the past, they were normally developed and investigated separately. Moreover, the accuracy of the previously proposed ... More
Bounded orbits of certain diagonalizable flows on $SL_{n}(\mathbb{R})/SL_{n}(\mathbb{Z})$May 27 2016We prove that the set of points that have bounded orbits under certain diagonalizable flows is a hyperplane absolute winning subset of $SL_{n}(\mathbb{R})/SL_{n}(\mathbb{Z})$.
Giant interfacial perpendicular magnetic anisotropy in MgO/CoFe/capping layer structuresMay 07 2016Sep 05 2016Magnetic tunnel junction (MTJ) based on CoFeB/MgO/CoFeB structures is of great interest due to its application in the spin-transfer-torque magnetic random access memory (STT-MRAM). Large interfacial perpendicular magnetic anisotropy (PMA) is required ... More
Convergence rates in homogenization of higher order parabolic systemsJan 08 2018This paper is concerned with the optimal convergence rate in homogenization of higher order parabolic systems with bounded measurable, rapidly oscillating periodic coefficients. The sharp $O(\va)$ convergence rate in the space $L^2(0,T; H^{m-1}(\Om))$ ... More
Receding Horizon Control Based Consensus Scheme in General Linear Multi-agent SystemsJun 24 2014This paper investigates the consensus problem of general linear multi-agent systems under the framework of optimization. A novel distributed receding horizon control (RHC) strategy for consensus is proposed. We show that the consensus protocol generated ... More
Unstable entropies and Dimension Theory of Partially Hyperbolic SystemsNov 09 2018In this paper we define unstable topological entropy for any subsets (not necessarily compact or invariant) in partially hyperbolic systems as a Carath\'{e}odory dimension characteristic, motivated by the work of Bowen and Pesin etc. We then establish ... More
Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structuresJun 12 2015Nov 16 2015Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses ... More
Optical control of magnetism in NiFe/VO2 heterostructuresMay 07 2018Oct 15 2018Optical methods for magnetism manipulation have been considered as a promising strategy for ultralow-power and ultrahigh-speed spin switches, which becomes a hot spot in the field of spintronics. However, a widely applicable and efficient method to combine ... More
Field-Free Switching of Perpendicular Magnetic Tunnel Junction via Voltage-Gated Spin Hall Effect for Low-Power Spintronic MemoryApr 30 2018Spin Hall effect (SHE) and voltage-controlled magnetic anisotropy (VCMA) are two promising methods for low-power electrical manipulation of magnetization. Recently, magnetic field-free switching of perpendicular magnetization through SHE has been reported ... More
Giant interfacial perpendicular magnetic anisotropy in MgO/CoFe/capping layer structuresMay 07 2016Dec 20 2016Magnetic tunnel junction (MTJ) based on CoFeB/MgO/CoFeB structures is of great interest due to its application in the spin-transfer-torque magnetic random access memory (STT-MRAM). Large interfacial perpendicular magnetic anisotropy (PMA) is required ... More
Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structuresJun 12 2015Feb 28 2017Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses ... More
Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistanceAug 14 2017Jan 23 2018Perpendicular magnetic tunnel junctions based on MgO/CoFeB structures are of particular interest for magnetic random-access memories because of their excellent thermal stability, scaling potential, and power dissipation. However, the major challenge of ... More
Large influence of capping layers on tunnel magnetoresistance in magnetic tunnel junctionsMay 22 2016Dec 28 2016It has been reported in experiments that capping layers which enhance the perpendicular magnetic anisotropy (PMA) of magnetic tunnel junctions (MTJs) induce great impact on the tunnel magnetoresistance (TMR). To explore the essential influence caused ... More
Broadband Magnetic-Manipulated Spintronic Terahertz Emitter with Arbitrarily Tunable PolarizationsSep 27 2018Flexible manipulation of terahertz-wave polarization during the generation process is very important for terahertz applications, especially for the next-generation on-chip functional terahertz sources. However, current terahertz emitters could not satisfy ... More
Domain-wall motion induced by spin transfer torque delivered by helicity-dependent femtosecond laserFeb 12 2019In magnetic wires with perpendicular anisotropy, moving domain with only current or only circularly polarized light requires a high power. Here, we propose to reduce it by using both short current pulses and femtosecond laser pulses simultaneously. The ... More
Large influence of capping layers on tunnel magnetoresistance in CoFe/MgO/CoFe magnetic tunnel junctionsMay 22 2016Sep 03 2016It has been investigated that capping layers which can enhance the perpendicular magnetic anisotropy (PMA) of magnetic tunnel junction (MTJ) induce great impact on the tunnel magnetoresistance (TMR). To explore the essential influence caused by capping ... More
Electric field control of domain wall logic in piezoelec-tric/ferromagnetic nanodevicesJan 24 2012Power dissipation is one of the most important factors limiting the future miniaturisation of integrated circuits. The capability of controlling magnetic states with a low voltage through magnetoelectric coupling in magnetostrictive/piezoelectric systems ... More
Optimization of high performance spintronic terahertz sourcesDec 06 2018Jan 31 2019To achieve high efficiency and good performance of spintronic terahertz sources, we propose and corroborate a remnant magnetization method to radiate continuously and stably terahertz pulses from W/CoFeB/Pt magnetic nanofilms without carrying magnets ... More
Convergence Rates in Almost-Periodic Homogenization of Higher-order Elliptic SystemsDec 05 2017This paper concentrates on the quantitative homogenization of higher-order elliptic systems with almost-periodic coefficients in bounded Lipschitz domains. For coefficients which are almost-periodic in the sense of H. Weyl, we establish uniform ocal $L^2$ ... More
Uniform Boundary Estimates in Homogenization of Higher Order Elliptic SystemsSep 13 2017This paper focuses on the uniform boundary estimates in homogenization of a family of higher order elliptic operators $\mathcal{L}_\epsilon$, with rapidly oscillating periodic coefficients. We derive uniform boundary $C^{m-1,\lambda} (0\!<\!\lambda\!<\!1)$, ... More
Birkhoff-von-Neumann Switches with Deflection-Compensated MechanismAug 20 2013Despite the high throughput and low complexity achieved by input scheduling based on Birkhoff-von-Neumann (BvN) decomposition; the performance of the BvN switch becomes less predictable when the input traffic is bursty. In this paper, we propose a deflection-compensated ... More
Domain Wall Motion Driven by Laplace Pressure in CoFeB-MgO Nanodots with Perpendicular AnisotropyNov 30 2017Apr 21 2018We have studied the magnetization reversal of CoFeB-MgO nanodots with perpendicular anisotropy for size ranging from w=400 nm to 1 {\mu}m. Contrary to previous experiments, the switching field distribution is shifted toward lower magnetic fields as the ... More
Brownian motion: from kinetics to hydrodynamicsJun 02 2017Brownian motion has served as a pilot of studies in diffusion and other transport phenomena for over a century. The foundation of Brownian motion, laid by Einstein, has generally been accepted to be far from being complete since the late 1960s, because ... More
Field-free switching of perpendicular magnetic tunnel junction by the interplay of spin orbit and spin transfer torquesJun 16 2018Spin-orbit torque and spin-transfer torque are leading the pathway to the future of spintronic memories. However, both of the mechanisms are suffering from intrinsic limitations. In particular, an external magnetic field is required for spin-orbit torque ... More
Heterogeneous Memristive Devices Enabled by Magnetic Tunnel Junction Nanopillars Surrounded by Resistive Silicon SwitchesAug 01 2017Mar 15 2018Emerging non-volatile memories (NVMs) have currently attracted great interest for their potential applications in advanced low-power information storage and processing technologies. Conventional NVMs, such as magnetic random access memory (MRAM) and resistive ... More
Description of Brownian motion including both kinetic and hydrodynamic effectsDec 02 2017Feb 12 2018It is known that a full description of Brownian motion in the entire course of time should incorporate both kinetic and hydrodynamic effects, but a formula accounts for both effects has been established only in three dimension and only for the limiting ... More
Femtosecond control of terahertz spin-charge conversion in ferromagnetic heterostructuresSep 14 2018Dec 01 2018Employing electron spin instead of charge to develop spintronic devices holds the merits of low-power consumption in information technologies. Meanwhile, the demand for increasing speed in spintronics beyond current CMOS technology has further triggered ... More
Unstable Entropy and Unstable Pressure for Random Diffeomorphisms with DominationNov 30 2018Let $\mathcal{F}$ be a $C^2$ random dynamical system with $u$-domination. For the unstable foliation, the corresponding unstable metric entropy, unstable topological entropy and unstable pressure via the dynamics of $\mathcal{F}$ on the unstable foliation ... More
On the ergodicity of geodesic flows on surfaces without focal pointsDec 11 2018In this article, we study the ergodicity of the geodesic flows on surfaces with no focal points. Let $M$ be a smooth connected and closed surface equipped with a $C^\infty$ Riemannian metric $g$, whose genus $\mathfrak{g} \geq 2$. Suppose that $(M,g)$ ... More
Convergence Rates and Interior Estimates in Homogenization of Higher Order Elliptic SystemsJun 07 2017This paper is concerned with the quantitative homogenization of $2m$-order elliptic systems with bounded measurable, rapidly oscillating periodic coefficients. We establish the sharp $O(\varepsilon)$ convergence rate in $W^{m-1, p_0}$ with $p_0=\frac{2d}{d-1}$ ... More
Unstable Entropies and Variational Principle for Partially Hyperbolic DiffeomorphismsOct 08 2017We study entropies caused by the unstable part of partially hyperbolic systems. We define unstable metric entropy and unstable topological entropy, and establish a variational principle for partially hyperbolic diffeomorphsims, which states that the unstable ... More
Ballistic Transport in One-Dimensional Quasi-Periodic Continuous Schrödinger EquationApr 01 2016Oct 04 2016For the solution $q(t)$ to the one-dimensional continuous Schr\"odinger equation $${\rm i}\partial_t{q}(x,t)=-\partial_x^2 q(x,t) + V(\omega x) q(x,t), \quad x\in{\Bbb R},$$ with $\omega\in{\Bbb R}^d$ satisfying a Diophantine condition, and $V$ a real-analytic ... More
Dispersion Relations and Polarizations of Low-frequency Waves in Two-fluid PlasmasMay 28 2015Analytical expressions for the dispersion relations and polarizations of low-frequency waves in magnetized plasmas based on two-fluid model are obtained. The properties of waves propagating at different angles (to the ambient magnetic field $\mathbf{B}_{0}$) ... More
On connectivity in a general random intersection graphAug 17 2015There has been growing interest in studies of general random intersection graphs. In this paper, we consider a general random intersection graph $\mathbb{G}(n,\overrightarrow{a}, \overrightarrow{K_n},P_n)$ defined on a set $\mathcal{V}_n$ comprising $n$ ... More
A mini review on the chemistry and catalysis of the water gas shift reactionSep 29 2014Water gas shift (WGS) reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen. It is an important reaction industrially used in conjunction with steam reforming of hydrocarbons for the production ... More
On the lower tail variational problem for random graphsFeb 03 2015We study the lower tail large deviation problem for subgraph counts in a random graph. Let $X_H$ denote the number of copies of $H$ in an Erd\H{o}s-R\'enyi random graph $\mathcal{G}(n,p)$. We are interested in estimating the lower tail probability $\mathbb{P}(X_H ... More
Understanding the radiative decays of vector charmonia to light pseudoscalar mesonsDec 06 2010Jan 24 2011We show that the newly measured branching ratios of vector charmonia ($J/\psi$, $\psi^\prime$ and $\psi(3770))$ into $\gamma P$, where $P$ stands for light pseudoscalar mesons $\pi^0$, $\eta$, and $\eta^\prime$, can be well understood in the framework ... More
The quadratic form in 9 prime variablesFeb 15 2014Let $f(x_1,\ldots,x_n)$ be a regular indefinite integral quadratic form with $n\ge 9$, and let $t$ be an integer. It is established that $f(x_1,\ldots,x_n)=t$ has solutions in prime variables if there are no local obstructions.
On restricted sumsets over a fieldFeb 14 2014We consider restricted sumsets over field $F$. Let\begin{align*}C=\{a_1+\cdots+a_n:a_1\in A_1,\ldots,a_n\in A_n, a_i-a_j\notin S_{ij}\ \text{if}\ i\not=j\},\end{align*} where $S_{ij}(1\leqslant i\not=j\leqslant n)$ are finite subsets of $F$ with cardinality ... More