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Electrical manipulation of skyrmions attracts considerable attention for its rich physics and promising applications. To date, such a manipulation is realized mainly via spin-polarized current based on spin-transfer torque or spin-orbital torque effect. However, this scheme is energy-consuming and may produce massive Joule heating. To reduce energy dissipation and risk of heightened temperatures of skyrmion-based devices, an effective solution is to use electric field instead of current as stimulus. Here, we realize an electric-field manipulation of skyrmions in a nanostructured ferromagnetic/ferroelectrical heterostructure at room temperature via an inverse magneto-mechanical effect. Intriguingly, such a manipulation is non-volatile and exhibits a multi-state feature. Numerical simulations indicate that the electric-field manipulation of skyrmions originates from strain-mediated modification of effective magnetic anisotropy and Dzyaloshinskii-Moriya interaction. Our results open a direction for constructing low-energy-dissipation, non-volatile, and multi-state skyrmion-based spintronic devices.

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attracted significant attention, which has a vast and growing number of military and civilian applications such as fire detection, missile interception, ozone hole monitoring, bioaerosol detection, astronomical imaging, and so on. [1][2][3] As the continuous improvement of devices integration, environment complexity, and interference technology, BUV photodetectors can effectively reduce false alarm rates in early warning, searching, and tracking systems, to improve the accuracy and versatility of detection systems in various situations. Many heterojunction structures based on wide-band-gap semiconductors have been reported to achieve the BUV photodetectors such as AlGaN/GaN, MgZnO/ZnO, and Ga 2 O 3 /GaN heterojunction. [4][5][6][7][8][9][10] However, AlGaN/GaN heterojunction has a high conduction band discontinuity which impedes the flow of photogenerated electrons and reduces the performance of photodetectors. [11] And high Mg-content MgZnO with high crystal quality is difficult to achieve by epitaxial growth due to the phase segregation in single wurtzite phase MgZnO. [12] β-Ga 2 O 3 with an ultrawide bandage of 4.9 eV is considered as a promising candidate for UV detection. [13,14] It has great thermal and chemical stability, determining its possibility of working at high temperatures and strong radiations. Moreover, there is a small lattice mismatch and a low conduction band offset at the interface between Ga 2 O 3 and GaN. These characteristics mean that Ga 2 O 3 /GaN heterojunction could be a potential for BUV photodetectors. Kalra et al. [6] demonstrated epitaxial β-Ga 2 O 3 /GaN-based vertical metal-heterojunctionmetal multiband UV photodetectors with the responsivity (R) of 3.7 A W −1 at 256 and 365 nm. For saving energy and broadening the application prospects of UV photodetectors, Guo et al. [15] fabricated a super-high-performance self-powered UV photodetector based on the GaN/Sn:Ga 2 O 3 p-n junction generated by depositing a Sn-doped n-type Ga 2 O 3 thin film onto a p-type GaN thick film. The responsivity at 254 nm reached up to 3.05 A W −1 without consuming external power. Lin et al. [16] used graphene as the transparent conductive layer to form graphene/β-Ga 2 O 3 /GaN heterojunction. With the help of largearea transparent electrode, a typical "sandwich" structure UV photodetector with low dark current density (1.25 × 10 −8 A cm −2 ) and high sensitivity (12.8 A W −1 ) was successfully assembled. Broadband ultraviolet (BUV) photodetectors responding to the multiband spectrum can effectively reduce false alarm rates and improve the accuracy and versatility of detection systems in various situations. A high-responsivityBUV photodetector based on vertical Ga 2 O 3 /GaN nanowire array is proposed and demonstrated. Ga 2 O 3 /GaN nanowires are obtained by partially thermally oxidizing GaN nanowires grown by molecular beam epitaxy and used to combine with a monolayer graphene film to form graphene/Ga 2 O 3 /GaN heterojunction. Moreover, the oxidation mechanism of GaN nanowires is further investigated by ...

Magnetic skyrmions are chiral quasiparticles that show promise for storage of information. At present, the achievable skyrmion density (η Sk ) is generally low (10−20 μm −2 ) because of the lack of effective manipulation. Here, both the magnetic anisotropy (K eff ) and interfacial Dzyaloshinskii−Moriya interaction (DMI) of [Pt/Co/Ta] n multilayer films are elaborately modulated by changing the Co thickness (t Co ) to study the η Sk dependence of intrinsic properties of the films systematically. The experimental and simulated results confirm that both the DMI and K eff have significant modifications on η Sk , and their respective contributions vary with t Co . Only when the magnetic anisotropy transits from out-of-plane to in-plane at an appropriate t Co range (1.8−2.1 nm) does the K eff decrease and the DMI increase with the t Co . Both the factors are favorable to the skyrmion formation and increase the density synergistically, toggling a maximal η Sk value of 45 μm −2 . These findings provide a criterion for designing the high η Sk magnetic film, which may advance the development of high-density skyrmion-based magnetic memorizers.

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In this paper, a solar-blind ultraviolet photodetector (PD) based on the graphene/vertical Ga2O3 nanowire array heterojunction was proposed and demonstrated. To the best of our knowledge, it is the first time that vertical Ga2O3 nanowire arrays have been realized. Ga2O3 nanowires were obtained by thermally oxidizing GaN nanowires grown by molecular beam epitaxy on n-doped Si substrate. Then, a monolayer graphene film was transferred to Ga2O3 nanowires to form the graphene/vertical Ga2O3 nanowire array heterojunction and transparent electrodes. The fabricated device exhibited a responsivity (R) of 0.185 A/W and rejection ratio (R258 nm/R365 nm) of 3×104 at the bias of −5 V. Moreover, the fast response times of this PD were 9 and 8 ms for the rise and decay times under 254 nm illumination, respectively, which are attributed to the unique properties of nanowire arrays and the graphene/vertical Ga2O3 nanowire array heterojunction structure.

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