We present a combined theoretical and experimental study of the ferromagnetic semiconductor (Ga,Mn)As which explains remarkably large changes observed on low-temperature annealing. Careful control annealing conditions allows us to obtain samples with transition temperatures up 159 K. Ab initio calculations, in situ Auger spectroscopy, resistivity measurements during show that are due out diffusion Mn interstitials towards surface, governed by an energy barrier 0.7-0.8 eV. Electric fields...

We report surface-bound growth of single-wall carbon nanotubes (SWNTs) at temperatures as low 350 degrees C by catalytic chemical vapor deposition from undiluted C2H2. NH3 or H2 exposure critically facilitates the nanostructuring and activation sub-nanometer Fe Al/Fe/Al multilayer catalyst films prior to growth, enabling SWNT nucleation lower temperatures. suggest that nanotube is governed surface without necessity liquefaction.

Abstract Restacking the exfoliated 2D layered materials into complex heterostructures with new functionality has opened a platform for engineering and device application. In this work, graphene sandwiched p‐GaSe/n‐WS 2 vertical are fabricated photodetection. The devices show excellent performance on photodetection from ultraviolet to visible wavelength range, including high photoresponsivity (≈149 A W −1 at 410 nm), short response time of 37 µs, self‐powered scanning photocurrent microscopy...

The integration of different two-dimensional materials within a multilayer van der Waals (vdW) heterostructure offers promising technology for high performance opto-electronic devices such as photodetectors and light sources. Here we report on the fabrication electronic properties vdW heterojunction diodes composed direct band gap layered semiconductors InSe GaSe transparent monolayer graphene electrodes. We show that type II alignment between two their distinctive spectral response,...

In order to increase the response speed of InSe‐based photodetector with high photoresponsivity, graphene is used as transparent electrodes modify difference work function between and InSe. As expected, InSe/graphene photodetectors down 120 μs, which about 40 times faster than that an InSe/metal device. It can also be tuned by back‐gate voltage from 310 μs 100 μs. With speed, photoresponsivity reach 60 A W −1 simultaneously. Meanwhile possess a broad spectral range at 400–1000 nm. The design...

Abstract Current‐induced magnetization switching by spin–orbit torque (SOT) holds considerable promise for next generation ultralow‐power memory and logic applications. In most cases, of torques has relied on an external injection out‐of‐plane spin currents into the magnetic layer, while field along electric current direction is generally required realizing deterministic SOT. Here, current‐induced SOT full lateral in zero reported. The Pt/Co/Pt structure locally annealed a laser track...

Magnetic tunnel junctions (MTJs) with conventional bulk ferromagnets separated by a nonmagnetic insulating layer are key building blocks in spintronics for magnetic sensors and memory. A radically different approach of using atomically-thin van der Waals (vdW) materials MTJs is expected to boost their figure merit, the tunneling magnetoresistance (TMR), while relaxing lattice-matching requirements from epitaxial growth supporting high-quality integration dissimilar atomically-sharp...

The emerging wide varieties of the van der Waals (vdW) magnets with atomically thin and smooth interfaces hold great promise for next-generation spintronic devices. However, due to lower Curie temperature vdW ferromagnets than room temperature, electrically manipulating its magnetization at has not been realized. In this work, it is demonstrated that perpendicular ferromagnet Fe3 GaTe2 can be effectively switched in /Pt bilayer by spin-orbit torques (SOTs) a relatively low current density...

Abstract Graphene and graphene‐like 2D layered materials such as black phosphorus, transition‐metal dichalcogenides, oxides, chalcogenides, so forth have attracted tremendous attention due to their unique crystal structures, mechanical, physical properties, well variable bandgaps that range from 0 6 eV, which offered utilization in versatile devices. Using these the active channel, many novel electrical optoelectronic devices been reported. Among various important applications,...

We investigated electrical and photoelectrical properties of graphene sandwiched WSe2/GaSe van der Waals heterojunctions. The device showed a high rectification ratio up to 300 at Vds = 1.5/−1.5 V, which is attributed the built-in electric field in device. Due bipolar property WSe2, gate-tunable inversion was observed. Meanwhile, heterojunction excellent performances on photodetection, where photoresponsivity (6.2 ± 0.2) A W−1 can be reached under −1.5 V P 0.2 μW. also great external quantum...

Photodetectors for the ultraviolet (UV) range of electromagnetic spectrum are in great demand several technologies, but require development novel device structures and materials. Here we report on high detectivity UV photodetectors based well-ordered laterally mesoporous GaN. The specific our devices under UV-illumination reaches values up to 5.3 × 1014 Jones. We attribute this properties GaN/metal contact interface: trapping photo-generated holes at interface lowers Schottky barrier height...

Abstract Electrical current–induced deterministic magnetization switching in a magnetic multilayer structure without any external field is realized by utilizing interlayer exchange coupling. Two ferromagnetic Co layers, with in‐plane and out‐of‐plane anisotropy, respectively, are separated spacer Ta layer, which plays dual role inducing antiferromagnetic coupling, contributing to the current‐induced effective through spin Hall effect. The behavior can be tuned premagnetizing layer. coupling...

Abstract A critical challenge for the integration of optoelectronics is that photodetectors have relatively poor sensitivities at nanometer scale. Generally, a large electrodes spacing in required to absorb sufficient light maintain high photoresponsivity and reduce dark current. However, this will limit optoelectronic density. Through spatially resolved photocurrent investigation, we find metal-semiconductor-metal (MSM) based on layered GaSe mainly generated from region close metal-GaSe...

Abstract Current induced magnetization switching by spin-orbit torques offers an energy-efficient means of writing information in heavy metal/ferromagnet (FM) multilayer systems. The relative contributions field-like and damping-like to the electrical current are still under debate. Here, we describe a device based on symmetric Pt/FM/Pt structure, which demonstrate strong torque from spin Hall effect unmeasurable Rashba effect. effective fields due were investigated quantitatively found be...

Atomically thin layered two-dimensional materials, including transition-metal dichacolgenide (TMDC) and black phosphorus (BP), (1) have been receiving much attention, because of their promising physical properties potential applications in flexible transparent electronic devices . Here, for the first time we show non-volatile chargetrap memory devices, based on field-effect transistors with large hysteresis, consisting a few-layer channel three dimensional (3D) Al2O3 /HfO2 /Al2O3 charge-trap...

Inspired by ion-dominated synaptic plasticity in human brain, artificial synapses for neuromorphic computing adopt charge-related quantities as their weights. Despite the existing charge derived emulations, schemes of controlling electron spins ferromagnetic devices have also attracted considerable interest due to advantages low energy consumption, unlimited endurance, and favorable CMOS compatibility. However, a generally applicable method tuning binary ferromagnet into multi-state memory...

We describe a spin logic device with controllable magnetization switching of perpendicularly magnetized ferromagnet / heavy metal structures on ferroelectric (1-x)[Pb(Mg1/3Nb2/3)O3]-x[PbTiO3] (PMN-PT) substrate using current-induced spin-orbit torque. The devices were operated without an external magnetic field and controlled by voltages as low 10 V applied across the PMN-PT substrate, which is much lower compared to previous reports (500 V). deterministic smaller voltage was realized from...

Abstract Atomically thin 2D materials are promising candidates for miniaturized high‐performance optoelectronic devices. This study reports on multilayer MoTe 2 photodetectors contacted with asymmetric electrodes based n‐ and p‐type graphene layers. The asymmetry in the contacts creates a large ( E bi ∼ 100 kV cm −1 ) built‐in electric field across short l = 15 nm) channel, causing high broad (λ 400–1400 photoresponse even without any externally applied voltage. Spatially resolved...

Non-collinear antiferromagnetic Weyl semimetals, combining the advantages of a zero stray field and ultrafast spin dynamics, as well large anomalous Hall effect chiral anomaly fermions, have attracted extensive interest. However, all-electrical control such systems at room temperature, crucial step toward practical application, has not been reported. Here, using small writing current density around 5 × 106 A·cm-2, we realize current-induced deterministic switching non-collinear...

GaN-based photodetectors are strongly desirable in many advanced fields, such as space communication, environmental monitoring, etc. However, the slow photo-response speed currently reported high-sensitivity still hinders their applications. Here, we demonstrate a and fast-speed UV photodetector based on asymmetric Au/nanoporous-GaN/graphene vertical junctions. The nanoporous shows an excellent rectification ratio up to ∼105 at +4 V/-4 V. photo-responsivity specific detectivity of device is...

Topologically protected magnetic "whirls" such as skyrmions in antiferromagnetic materials have recently attracted extensive interest due to their nontrivial band topology and potential application spintronics. However, room-temperature natural metallic with merit of probable convenient electrical manipulation not been reported. Here, are realized a non-collinear antiferromagnet, Mn3 Sn, capped Pt overlayer. The evolution spin textures from coplanar inverted triangular structures Bloch-type...

We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy fields in results a spin reorientation transition an anisotropic ac susceptibility which is fully consistent with simple single-domain model. The constants vary, respectively, as square fourth power spontaneous magnetization across whole temperature range up to . weakening at may be technological importance for applications involving thermally assisted switching.

Abstract Emerging 2D metal chalcogenides present excellent performance for electronic and optoelectronic applications. In contrast to graphene other materials, possess intrinsic bandgaps, versatile band structures, superior atmospheric stability. The many categories of ensure that they can be applied various practical scenarios. monochalcogenides, dichalcogenides, trichalcogenides are the three main these materials. They have distinct crystal structures resulting in different...