Programmable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a ...centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices.
Ultraviolet (UV) photodetectors with high responsivity and fast response are crucial for practical applications. Double perovskite Cs2AgBiBr6 has emerged as a promising optoelectronic material due to ...its excellent physics and photoelectric properties. However, no work is reported based on its film for photodetector applications. Herein, an ITO/SnO2/Cs2AgBiBr6/Au hole‐transport layer free planar heterojunction device is fabricated for photodetector application. The device is self‐powered with two responsivity peaks at 350 and 435 nm, which is suitable for ultraviolet‐A (320–400 nm) and deep‐blue light detecting. A high responsivity of 0.11 A W−1 at 350 nm and a quick response time of less than 3 ms are obtained, which is significantly higher than other semiconductor oxide heterojunction‐based UV detectors. More importantly, the stability is significantly better than most of the hybrid perovskite photodetectors reported so far. Its photocurrent shows no obvious degradation after more than 6 months storage in ambient conditions without any encapsulation. Consequently, the utilization of Cs2AgBiBr6 film is a practical approach for high performance, large‐area lead‐free perovskite photodetector applications. For the mechanism, it is found that photogenerated carriers in Cs2AgBiBr6 film are separated at the Cs2AgBiBr6/SnO2 heterojunction interface by its built‐in field. The low toxicity and high stability of this double perovskite active layer make it very promising for practical applications.
A high‐quality lead‐free double perovskite Cs2AgBiBr6 film based self‐powered photo‐detector is successfully demonstrated. The device with Cs2AgBiBr6/SnO2 heterojunction shows good wavelength selectivity for UV‐A and blue light. As an UV detector, its performance is much higher than other semiconductor oxide heterojunction‐based devices. In addition, this device has excellent stability in ambient conditions. It is believed that the double perovskite Cs2AgBiBr6 film based photodetector can be commercialized due to its low toxicity and excellent intrinsic stability.
Large-area vertical rutile TiO
2
nanorod arrays (TNAs) were grown on F/SnO
2
conductive glass using a hydrothermal method at low temperature. A self-powered ultraviolet (UV) photodetector based on ...TiO
2
nanorod/water solid–liquid heterojunction is designed and fabricated. These nanorods offer an enlarged TiO
2
/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. A photosensitivity of 0.025 A/W and a quick response time were observed. At the same time, a high photosensitivity in a wide range of wavelength was also demonstrated. This TNA/water UV detector can be a particularly suitable candidate for practical applications for its high photosensitivity, fast response, excellent spectral selectivity, uncomplicated low-cost fabrication process, and environment-friendly feature.
Flexible and self-powered ultraviolet (UV) photodetectors can meet the growing demand of next-generation portable, light-weight optoelectronic devices and have attracted increasing attention in ...recent years. However, it is still challenging to develop self-powered UV detectors with high photosensitivity, fast response time, environment-friendly feature, as well as compatible to flexible substrates. Herein, thin film UV photodetectors based on inorganic ZnO/SrCoOx heterojunction are designed and fabricated on flexible polyimide substrate at room temperature. The built-in electric field between n-type ZnO and p-type SrCoOx films facilitates the separation and transportation of photogenerated carriers without any external bias. A high photosensitivity of (73.8 mA/W) and a quick response time (0.6/4.8 ms) at zero bias are realized under UV light illumination. Moreover, a long-term stability and a good flexibility are also demonstrated. This self-powered flexible UV photodetector fabricated at room temperature is a promising candidate for future energy-efficient, wearable and lightweight optoelectronic devices.
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•Amorphous SrCoOx film, for the first time, is adopted as the p-type semiconductor in optoelectronic devices.•Full oxide ZnO/SrCoOx heterojunction was designed and fabricated for self-powered ultraviolet photodetectors.•A highest photosensitivity of 73.8 mA/W and a rapid response time of 0.6/4.8 ms were observed in this photodetector.•Long-term stability and good flexibility of this self-powered photodetector were demonstrated.
Photoelectrochemical cell-typed self-powered UV detectors have attracted intensive research interest due to their low cost, simple fabrication process, and fast response. In this paper, SnO
2
-TiO
2
...nanomace arrays composed of SnO
2
nanotube trunk and TiO
2
nanobranches were prepared using soft chemical methods, and an environment-friendly self-powered UV photodetector using this nanostructure as the photoanode was assembled. Due to the synergistic effect of greatly accelerated electron-hole separation, enhanced surface area, and reduced charge recombination provided by SnO
2
-TiO
2
nanomace array, the nanostructured detector displays an excellent performance over that based on bare SnO
2
arrays. The impact of the growing time of TiO
2
branches on the performance of UV photodetector was systematically studied. The device based on optimized SnO
2
-TiO
2
nanomace arrays exhibits a high responsivity of 0.145 A/W at 365 nm, a fast rising time of 0.037 s, and a decay time of 0.015 s, as well as excellent spectral selectivity. This self-powered photodetector is a promising candidate for high-sensitivity, high-speed UV-detecting application.
Coherent light sources in the visible range are playing important roles in our daily life and modern technology, since about 50% of the capability of the our human brains is devoted to processing ...visual information. Visible lasers can be achieved by nonlinear optical process of infrared lasers and direct lasing of gain materials, and the latter has advantages in the aspects of compactness, efficiency, simplicity, etc. However, due to lack of visible optical modulators, the directly generated visible lasers with only a gain material are constrained in continuous-wave operation. Here, we demonstrated the fabrication of a visible optical modulator and pulsed visible lasers based on atomic-layer molybdenum sulfide (MoS2), a ultrathin two-dimensional material with about 9-10 layers. By employing the nonlinear absorption of the modulator, the pulsed orange, red and deep red lasers were directly generated. Besides, the present atomic-layer MoS2 optical modulator has broadband modulating properties and advantages in the simple preparation process. The present results experimentally verify the theoretical prediction for the low-dimensional optoelectronic modulating devices in the visible wavelength region and may open an attractive avenue for removing a stumbling block for the further development of pulsed visible lasers.
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•Solid-state synaptic transistor using SrFeO2.5 channel was designed and fabricated.•An excellent symmetric behavior with an asymmetric ratio of only 0.19 is achieved.•A high level of ...MNIST pattern recognition accuracy (97.3%) was obtained.
In the past few years, synaptic device has become a hot topic in material science because of the urgent demand of neuromorphic computing. Ionic liquids gated three-terminal synaptic transistors have drawn extensive attention due to their outstanding energy efficiency, linearity, and symmetry. However, utilization of liquid electrolyte is not appropriate for the requirement of the practical application. Herein, a novel three-terminal synaptic transistor is designed and constructed using a solid-state electrolyte gate and a brownmillerite SrFeO2.5 thin film channel. Topotactic phase transformation can be induced between insulative brownmillerite SrFeO2.5 and conductive perovskite SrFeO3−δ. Nonvolatile conductance switching of the SrFeOx film can be realized by inserting and extracting of oxygen ions with electrolyte gating. The essential synaptic learning functions including excitatory postsynaptic current, and short-term/long-term plasticity, are successfully mimicked in the three-terminal synaptic transistor. This synapse device achieves a large scale adjusted range and multistable plasticity, demonstrating a new way to achieve key component of upcoming neuromorphic circuitry.
Lithium-ion (Li-ion) batteries based on spinel transition-metal oxide electrodes have exhibited excellent electrochemical performance. The reversible intercalation/deintercalation of Li-ions in ...spinel materials enables not only energy storage but also nondestructive control of the electrodes' physical properties. This feature will benefit the fabrication of novel Li-ion controlled electronic devices. In this work, reversible control of ferromagnetism was realized by the guided motion of Li-ions in MnFe
O
and γ-Fe
O
utilizing miniature lithium-battery devices. The in-situ characterization of magnetization during the Li-ion intercalation/deintercalation process was conducted, and a reversible variation of saturation magnetization over 10% was observed in both these materials. The experimental conditions and material parameters for the control of the ferromagnetism are investigated, and the mechanism related to the magnetic ions' migration and the exchange coupling evolution during this process was proposed. The different valence states of tetrahedral metal ions were suggested to be responsible for the different performance of these two spinel materials.
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