Thermoelectric Transport Performance in p-Type AgSbTe-Based Materials through Entropy Engineering.

Being a major obstacle, AgTe has always been restricted in p-type AgSbTe-based materials to improve their thermoelectric performance. This work reveals a stabilized AgSbTe through Sn/Ge alloying as synthesized by melting, annealing, and hot press. Interestingly, addition of Sn/Ge in AgSbTe extended the solubility limit up to ∼30% and hence suppressed AgTe in AgSnSbGeTe compounds and led to enhanced electrical transport.

Band Position-Independent Piezo-Electrocatalysis for Ultrahigh CO Conversion.

Piezo-electrocatalysis as an emerging mechano-to-chemistry energy conversion technique opens multiple innovative opportunities and draws great interest over the past decade. However, the two potential mechanisms in piezo-electrocatalysis, i.e.

Multi-Level Resistive Switching in SnSe/SrTiO Heterostructure Based Memristor Device.

Multilevel resistive switching in memristive devices is vital for applications in non-volatile memory and neuromorphic computing. In this study, we report on the multilevel resistive switching characteristics in SnSe/SrTiO(STO) heterojunction-based memory devices with silver (Ag) and copper (Cu) top electrodes. The SnSe/STO-based memory devices present bipolar resistive switching (RS) with two orders of magnitude on/off ratio, which is reliable and stable.

Enhancement of ferroelectricity and homogeneity of orthorhombic phase in HfZrOthin films.

By adoption of a high permittivity ZrOcapping layer (ZOCL), enhanced ferroelectric properties were achieved in the HfZrO(HZO) thin films. For HZO thin film with 10 Å ZOCL, the 2value can reach as high as ∼43.1C cmunder a sweep electric field of 3 MV cm.

Flexoelectric Thin-Film Photodetectors.

The flexoelectric effect, which manifests itself as a strain-gradient-induced electrical polarization, has triggered great interest due to its ubiquitous existence in crystalline materials without the limitation of lattice symmetry. Here, we propose a flexoelectric photodetector based on a thin-film heterostructure. This prototypical device is demonstrated by epitaxial LaFeO thin films grown on LaAlO substrates.

Modulating Magnetism in Ferroelectric Polymer-Gated Perovskite Manganite Films with Moderate Gate Pulse Chains.

Most previous attempts on achieving electric-field manipulation of ferromagnetism in complex oxides, such as LaSrMnO (LSMO), are based on electrostatically induced charge carrier changes through high- dielectrics or ferroelectrics. Here, the use of a ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene [P(VDF-TrFE)], as a gate dielectric to successfully modulate the ferromagnetism of the LSMO thin film in a field-effect device geometry is demonstrated. Specifically, through the application of low-voltage pulse chains inadequate to switch the electric dipoles of the copolymer, enhanced tunability of the oxide magnetic response is obtained, compared to that induced by ferroelectric polarization.

High-Temperature Anomalous Hall Effect in a Transition Metal Dichalcogenide Ferromagnetic Insulator Heterostructure.

Integration of transition metal dichalcogenides (TMDs) on ferromagnetic materials (FM) may yield fascinating physics and promise for electronics and spintronic applications. In this work, high-temperature anomalous Hall effect (AHE) in the TMD ZrTe thin film using a heterostructure approach by depositing it on a ferrimagnetic insulator YIG (YFeO, yttrium iron garnet) is demonstrated. In this heterostructure, significant anomalous Hall effect can be observed at temperatures up to at least 400 K, which is a record high temperature for the observation of AHE in TMDs, and the large is more than 1 order of magnitude larger than those previously reported values in topological insulators or TMD-based heterostructures.

A dual mode electronic synapse based on layered SnSe films fabricated by pulsed laser deposition.

An artificial synapse, such as a memristive electronic synapse, has caught world-wide attention due to its potential in neuromorphic computing, which may tremendously reduce computer volume and energy consumption. The introduction of layered two-dimensional materials has been reported to enhance the performance of the memristive electronic synapse. However, it is still a challenge to fabricate large-area layered two-dimensional films by scalable methods, which has greatly limited the industrial application potential of two-dimensional materials.

Thickness-dependent magnetotransport properties in 1T VSe single crystals prepared by chemical vapor deposition.

Two-dimensional (2D) metallic transition metal dichalcogenides (TMDs) exhibit fascinating quantum effects, such as charge-density-wave (CDW) and weak antilocalization (WAL) effect. Herein, low temperature synthesis of 1T phase VSe single crystals with thickness ranging from 3 to 41 nm by chemical vapor deposition (CVD) is reported. The VSe shows a decreasing phase transition temperature of the CDW when the thickness is decreased.

Log-periodic quantum magneto-oscillations and discrete-scale invariance in topological material HfTe.

Discrete-scale invariance (DSI) is a phenomenon featuring intriguing log-periodicity that can be rarely observed in quantum systems. Here, we report the log-periodic quantum oscillations in the longitudinal magnetoresistivity ( ) and the Hall traces ( ) of HfTe crystals, which reveal the DSI in the transport-coefficients matrix. The oscillations in and show the consistent log-periodicity with a phase shift.

Modulating the Electrical Transport in the Two-Dimensional Electron Gas at LaAlO_{3}/SrTiO_{3} Heterostructures by Interfacial Flexoelectricity.

Thin film flexoelectricity is attracting more attention because of its enhanced effect and potential application in electronic devices. Here we find that a mechanical bending induced flexoelectricity significantly modulates the electrical transport properties of the interfacial two-dimensional electron gas (2DEG) at the LaAlO_{3}/SrTiO_{3} (LAO/STO) heterostructure. Under variant bending states, both the carrier density and mobility of the 2DEG are changed according to the flexoelectric polarization direction, showing an electric field effect modulation.

Magnetotransport Properties of Layered Topological Material ZrTe Thin Film.

ZrTe is a candidate topological material from the layered two-dimensional transition-metal dichalcogenide family, and thus the material may show exotic electrical transport properties and may be promising for quantum device applications. In this work, we report the successful growth of layered ZrTe thin film by pulsed-laser deposition and the experimental results of its magnetotransport properties. In the presence of a perpendicular magnetic field, the 60 nm thick ZrTe film shows a large magnetoresistance of 3000% at 2 K and 9 T.

Discovery of log-periodic oscillations in ultraquantum topological materials.

Quantum oscillations are usually the manifestation of the underlying physical nature in condensed matter systems. Here, we report a new type of log-periodic quantum oscillations in ultraquantum three-dimensional topological materials. Beyond the quantum limit (QL), we observe the log-periodic oscillations involving up to five oscillating cycles (five peaks and five dips) on the magnetoresistance of high-quality single-crystal ZrTe, virtually showing the clearest feature of discrete scale invariance (DSI).

Self-Powered Ultrabroadband Photodetector Monolithically Integrated on a PMN-PT Ferroelectric Single Crystal.

Photodetectors capable of detecting two or more bands simultaneously with a single system have attracted extensive attentions because of their critical applications in image sensing, communication, and so on. Here, we demonstrate a self-powered ultrabroadband photodetector monolithically integrated on a 0.72Pb(MgNb)O-0.

Infrared light gated MoS₂ field effect transistor.

Molybdenum disulfide (MoS₂) as a promising 2D material has attracted extensive attentions due to its unique physical, optical and electrical properties. In this work, we demonstrate an infrared (IR) light gated MoS₂ transistor through a device composed of MoS₂ monolayer and a ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O₃-PbTiO₃ (PMN-PT). With a monolayer MoS₂ onto the top surface of (111) PMN-PT crystal, the drain current of MoS₂ channel can be modulated with infrared illumination and this modulation process is reversible.

Enhanced surface-and-interface coupling in Pd-nanoparticle-coated LaAlO3/SrTiO3 heterostructures: strong gas- and photo-induced conductance modulation.

Pd nanoparticle (NP) coated LaAlO3/SrTiO3 (LAO/STO) heterointerface exhibits more notable conductance (G) change while varying the ambient gas (N2, H2/N2, and O2) and illuminating with UV light (wavelength: 365 nm) than a sample without the NPs. Simultaneous Kelvin probe force microscopy and transport measurements reveal close relationships between the surface work function (W) and G of the samples. Quantitative analyses suggest that a surface adsorption/desorption-mediated reaction and redox, resulting in a band-alignment modification and charge-transfer, could explain the gas- and photo-induced conductance modulation at the LAO/STO interface.

Broadband focusing ultrasonic transducers based on dimpled LiNbO3 plate with inversion layer.

A high-frequency broadband focusing transducer based on dimpled LiNbO(3) inversion layer plate has been fabricated and characterized. A spherical surface with a curvature radius of 6 mm is formed on the half-thickness LiNbO(3) inversion layer plate of Y36° cut orientation. The domain structure in the cross section is observed after a hydrofluoric acid etching process.

High-sensitivity fiber-tip pressure sensor with graphene diaphragm.

A miniature fiber-tip pressure sensor was built by using an extremely thin graphene film as the diaphragm. The graphene also acts as a light reflector, which, in conjunction with the reflection at the fiber end-air interface, forms a low finesse Fabry-Perot interferometer. The graphene based sensor demonstrated pressure sensitivity over 39.

High-frequency ultrasonic transducer fabricated with lead-free piezoelectric single crystal.

High-frequency (25 MHz) ultrasonic transducers with Na(0.5)Bi(0.5)TiO(3)-BaTiO(3) (NBT-BT) lead-free piezoelectric single crystal as the active elements are fabricated and characterized.

Ferroelectric domain in PMN-xPT single crystal studied by piezoresponse force microscopy and finite-element analysis.

Ferroelectric domain structures in (001)-cut Pb(Mg(1/3)Nb(2/3))O(3)-38%PbTiO(3) and (011)-cut Pb(Mg(1/3) Nb(2/3))O(3)-60%PbTiO(3) single crystals are studied by means of piezoresponse force microscopy (PFM). The out-of-plane- polarization (OPP) and in-plane-polarization (IPP) domain piezoresponse imaging reveals the domain and domain boundary configurations in these two different PbTiO(3)-content crystals. Finite-element analysis is carried out to illustrate the OPP and IPP-PFM imagings mechanism and interpret the domains superposition phenomenon during PFM imaging.