A5082201469- Magnetic properties of thin films
- Multiferroics and related materials
- Advanced Chemical Physics Studies
- Magnetic and transport properties of perovskites and related materials
- ZnO doping and properties
- Magnetic Properties and Applications
- Quantum and electron transport phenomena
- RNA and protein synthesis mechanisms
- Physics of Superconductivity and Magnetism
- Molecular Junctions and Nanostructures
- Surface Chemistry and Catalysis
- Topological Materials and Phenomena
- nanoparticles nucleation surface interactions
- RNA modifications and cancer
- Ferroelectric and Piezoelectric Materials
- Advanced Condensed Matter Physics
- Atomic and Molecular Physics
- DNA and Nucleic Acid Chemistry
- Magneto-Optical Properties and Applications
- Graphene research and applications
- Surface and Thin Film Phenomena
- Spectroscopy and Quantum Chemical Studies
- Advanced Memory and Neural Computing
- Magnetic Field Sensors Techniques
- Theoretical and Computational Physics
University of California, Los Angeles
2014-2023
University of California System
2004-2023
Institute of Physics
2016-2021
Chinese Academy of Sciences
2016-2021
Sichuan University
2021
Fudan University
2016
Inston (United States)
2016
IBM Research - Thomas J. Watson Research Center
2016
University of California, Berkeley
2014
University of California, Riverside
1974-2011
Magnetic skyrmions, which are topologically protected spin textures, promising candidates for ultralow-energy and ultrahigh-density magnetic data storage computing applications. To date, most experiments on skyrmions have been carried out at low temperatures. The choice of available materials is limited, there a lack electrical means to control in devices. In this work, we demonstrate new method creating stable skyrmion bubble phase the CoFeB–MgO material system room temperature, by...
Abstract The promise of high-density and low-energy-consumption devices motivates the search for layered structures that stabilize chiral spin textures such as topologically protected skyrmions. At same time, recently discovered long-range intrinsic magnetic orders in two-dimensional van der Waals materials provide a new platform discovery novel physics effects. Here we demonstrate Dzyaloshinskii–Moriya interaction Néel-type skyrmions are induced at WTe 2 /Fe 3 GeTe interface. Transport...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Tao Wu, Alexandre Bur, Ping Zhao, Kotekar P. Mohanchandra, Kin Wong, Kang L. Wang, Christopher S. Lynch, Gregory Carman; Giant electric-field-induced reversible permanent magnetization reorientation on magnetoelectric Ni/(011) [Pb(Mg1/3Nb2/3)O3](1−x)–[PbTiO3]x heterostructure. Appl. Phys. Lett. 3 January 2011;...
Introducing magnetic order in a topological insulator (TI) breaks time-reversal symmetry of the surface states and can thus yield variety interesting physics promises for novel spintronic devices. To date, however, effects TIs have been demonstrated only at temperatures far below those needed practical applications. In this work, we study properties Bi2Se3 (SS) proximity high Tc ferrimagnetic (FMI), yttrium iron garnet (YIG or Y3Fe5O12). Proximity-induced butterfly square-shaped...
Spin-momentum locked surface states in topological insulators (TIs) provide a promising route for achieving high spin-orbit torque (SOT) efficiency beyond the bulk coupling heavy metals (HMs). However, previous works, there is huge discrepancy among quantitative SOTs from TIs various systems determined by different methods. Here, we systematically study SOT TI(HM)/Ti/CoFeB/MgO same method, and make conclusive assessment of HMs. Our results demonstrate that show more than one order magnitude...
Giant spin-orbit torque (SOT) from topological insulators (TIs) provides an energy efficient writing method for magnetic memory, which, however, is still premature practical applications due to the challenge of integration with tunnel junctions (MTJs). Here, we demonstrate a functional TI-MTJ device that could become core element future energy-efficient spintronic devices, such as SOT-based random-access memory (SOT-MRAM). The state-of-the-art tunneling magnetoresistance (TMR) ratio 102% and...
Anthraquinone molecules self-assemble on a Cu(111) surface into large two-dimensional honeycomb network (square root of 304 x square 304)R23 degrees with pore diameters approximately 50 A. The spontaneous formation pattern containing pores roughly five times larger than the size constituent is unprecedented. originates from delicate balance between substrate-mediated repulsion and intermolecular attraction involving an unusual chemical motif: hydrogen bonding carbonyl oxygen aromatic atom....
We report giant reversible and permanent magnetic anisotropy reorientation between two perpendicular easy axes in a magnetoelectric polycrystalline Ni thin film (011) oriented [Pb(Mg1/3Nb2/3)O3](1−x)-[PbTiO3]x (PMN-PT) heterostructure. The PMN-PT is partially poled prior to deposition provide remanent strain bias. Following full poling of the sample, strains equal opposite values are used reversibly permanently reorient magnetization state film. These experimental results integrated into...
In this work, we report on the demonstration of voltage-driven spin wave excitation, where waves are generated by multiferroic magnetoelectric (ME) cell transducers driven an alternating voltage, rather than electric current. A element consisting a magnetostrictive Ni film and piezoelectric [Pb(Mg1/3Nb2/3)O3](1−x)–[PbTiO3]x substrate was used for purpose. By applying AC voltage to piezoelectric, oscillating field is created within material, which results in strain-induced magnetic anisotropy...
The ferroelectric properties of (011) [Pb(Mg1/3Nb2/3)O3](1−x)-[PbTiO3]x (PMN-PT, x≈0.32) single crystals with focus on piezoelectric strain response were reported. Two giant reversible and stable remanent states tunable are achieved by properly reversing the electric field from depolarized direction. unique response, especially along [100] direction, mainly stems non-180° polarization reorientation in rhombohedral phase crystal structure. Such hysteresis may be useful for magnetoelectric...
We review the recent progress in development of magnetoelectric RAM (MeRAM) based on electric-field-controlled writing magnetic tunnel junctions (MTJs). MeRAM uses tunneling magnetoresistance effect for readout a two-terminal memory element, similar to other types RAM. However, information is performed by voltage control anisotropy (VCMA) at interface an MgO barrier and CoFeB-based free layer, as opposed current-controlled (e.g., spin-transfer torque or spin-orbit torque) mechanisms. present...
Thermally induced domain wall motion in a magnetic insulator was observed using spatiotemporally resolved polar magneto-optical Kerr effect microscopy. The following results were found: (i) the moves towards hot regime; (ii) threshold temperature gradient (5 K/mm), i.e., minimal required to induce motion; (iii) finite velocity outside of region with gradient, slowly decreasing as function distance, which is interpreted result from penetration magnonic current into constant region; and (iv)...
The influence of spin-Hall-effect spin torque (SHE-ST) induced by in-plane charge current was studied in microscale Ta/Co${}_{20}$Fe${}_{60}$B${}_{20}$/TaO${}_{x}$ films with perpendicular magnetization. Simultaneous electrical transport and polar magneto-optical Kerr effect (MOKE) imaging experiments were used to investigate the switching dynamics. A rich set behaviors observed, which can be well understood analyzing a switching-phase diagram MOKE images, considering competition between...
We studied the impact of different insertion layers (Ta, Pt, and Mg) at CoFeB|MgO interface on voltage-controlled magnetic anisotropy (VCMA) effect other properties. Inserting a very thin Mg layer 0.1–0.3 nm yielded VCMA coefficient 100 fJ/V-m, more than 3 times higher average values around 30 fJ/V-m reported in Ta|CoFeB|MgO-based structures. Ta Pt also showed small improvement, yielding coefficients 40 fJ/V-m. Electrical, magnetic, X-ray diffraction results reveal that 1.2 gives rise to...
Utilizing spin-orbit torque (SOT) to switch a magnetic moment provides promising route for low-power-dissipation spintronic devices. Here, the SOT switching of nearly compensated ferrimagnet Gdx (FeCo)1-x by topological insulator [Bi2 Se3 and (BiSb)2 Te3 ] is investigated at room temperature. The current density (1.20 × 105 A cm-2 ) more than one order magnitude smaller that in conventional heavy-metal-based structures, which indicates ultrahigh efficiency charge-spin conversion (>1) surface...
We demonstrate strain-induced modulation of perpendicular magnetic anisotropy (PMA) in (001)-oriented [Pb(Mg1/3Nb2/3)O3](1−x)-[PbTiO3]x (PMN-PT) substrate/Ta/CoFeB/MgO/Ta structures using ferromagnetic resonance (FMR). An in-plane biaxial strain is produced by applying voltage between the two surfaces PMN-PT substrate, and transferred to CoFeB layer, which results tuning PMA layer. The change quantitatively extracted from experimental FMR spectra. It shown that both first second-order terms...
Manipulating magnetism by electric current is of great interest for both fundamental and technological reasons. Much effort has been dedicated to spin-orbit torques (SOTs) in metallic structures, while quantitative investigation analogous phenomena magnetic insulators remains challenging due their low electrical conductivity. Here we address this challenge exploiting the interaction light with order, directly measure SOTs insulating structures. The equivalency optical transport measurements...
Symmetry breaking is a characteristic to determine which branch of bifurcation system follows upon crossing critical point. Specifically, in spin–orbit torque (SOT) devices, fundamental question arises: how can the symmetry perpendicular magnetic moment be broken by in-plane spin polarization? Here, we show that chiral antisymmetric Dzyaloshinskii–Moriya interaction (DMI) induce deterministic SOT switching magnetization. By introducing gradient saturation magnetization or anisotropy, dynamic...
The Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric exchange that stabilizes spin chirality. One scientific and technological challenge understanding controlling the between chirality electric field. In this study, we investigate unconventional field effect on interfacial DMI, skyrmion helicity, dynamics in a system with broken inversion symmetry. We design heterostructures 3d-5d atomic orbital interface to demonstrate gate bias control of DMI energy thus transform opposite...
Surface safari: 9,10-Anthracenedicarbonitrile (DCA) molecules adsorbed on a Cu(111) surface can be titrated by gradual annealing of the substrate to form trigonal planar Cu(DCA)3 complexes and, ultimately, hexagonal network (see picture) with Cu2(DCA)3 stoichiometry. As result charge donation from substrate, coordinated Cu adatom remains electrically neutral despite donating approximately 1/3 each CuN bond. Detailed facts importance specialist readers are published as "Supporting...
We study the current-driven perpendicular magnetization switching in Ta/CoFeB(wedge)/[TaOx or MgO/TaOx] devices with a lateral structural asymmetry introduced by varying CoFeB thickness. In these devices, an in-plane current can generate field-like torque and its corresponding effective magnetic field (HzFL) is out-of-plane, which deterministically switch at zero field. Experimental results indicate that method used for breaking symmetry greatly affects resulting torque, gradient of...
A new class of devices based on topological insulators (TI) can be achieved by the direct engineering time-reversal-symmetry (TRS) protected surface states. In meantime, a variety interesting phenomena are also expected when additional ferromagnetism is introduced to original order. this Letter, we report magnetic responses from magnetically modulation-doped (BizSb1–z)2Te3/Crx(BiySb1–y)2Te3 bilayer films. By electrically tuning Fermi level across Dirac point, show that top TI carriers...