Npg Asia Materials最新文献

Manipulating the topological properties of spin textures in magnetic materials is of great interest due to the rich physics and promising technological applications of these materials in advanced electronic devices. A spin texture with desired topological properties can be created by magnetic monopole injection, resulting in topological transitions involving changes in the topological charge. Therefore, controlling magnetic monopole injection has paramount importance for obtaining the desired spin textures but has not yet been reported. Here, we report the use of reliably manipulated magnetic monopole injection in the topological transition from stripe domains to skyrmions in an Fe/Gd multilayer. An easily tunable in-plane magnetic field applied to an Fe/Gd multilayer plays a key role in the magnetic monopole injection by modulating the local exchange energy. Our findings facilitate the efficient management of topological transitions by providing an important method for controlling magnetic monopole injection.

Real-time monitoring and early warning of human health conditions is an important function of wearable devices. Along with the development of the Internet of Things and the medical drive for early detection and treatment, wearable devices will become increasingly important in the future. Compared with traditional sensors, wearable sensors with mechanical softness and deformability are able to adapt to geometric nonlinearities and deformations caused by motion that occurs in application scenarios, thus ensuring stable and effective signal output under various complex working conditions. Various novel sensing materials have been developed for the detection of various biomarkers of respiration over the past few years. Here, we summarize the latest innovations in wearable respiratory sensors, highlighting the dominant sensing materials, designs, sensing mechanisms, and clinical implications. Finally, the future challenges and directions of wearable respiratory sensors are outlined toward promoting advancement in the field of wearable respiratory monitoring.

The human cutaneous lymphatic system strictly controls lymphatic functions by coordinating with skin cells. The lymphatic system plays important roles in removing cell waste, residual proteins, various antigens, and immune cells from tissues to maintain homeostasis and activate the immune system through the drainage of interstitial fluid^1,2. The skin protects our body from external stimuli such as pathogens through the cutaneous lymphatic system^3,4. Herein, to develop an in vitro human cutaneous lymphatic model, we present two 3D microfluidic platforms: a lymphangiogenesis model with a precollecting lymphatic vessel-like structure and an advanced lymphangiogenesis model with a functional cutaneous barrier and a precollecting lymphatic vessel-like structure. In addition, we rapidly analyzed prolymphangiogenic effects using methods that incorporate a high-speed image processing system and a deep learning-based vascular network analysis algorithm by 12 indices. Using these platforms, we evaluated the pro-lymphangiogenic effect of Lymphanax, a natural product derived from fresh ginseng. As a result, we demonstrated that Lymphanax induces robust lymphangiogenesis without any structural abnormalities. In conclusion, we suggest that these innovative platforms are useful for studying the interaction between the skin and lymphatic system as well as evaluating the prolymphangiogenic effects of drugs and cosmetics.

Anomalous transverse conductivities, such as anomalous Hall conductivity (AHC), anomalous Nernst conductivity (ANC), and anomalous thermal Hall conductivity (ATHC), play a crucial role in the emerging field of spintronics. Motivated by the recent fabrication of two-dimensional (2D) ferromagnetic thin film Fe₃GaTe₂, we investigate the thickness-dependent anomalous transverse conductivities of the 2D Fe₃GaTe₂ system (from one to four layers). The atomically ultrathin 2D Fe₃GaTe₂ system shows above-room-temperature ferromagnetism with a large perpendicular magnetic anisotropy energy. Furthermore, we obtain a large AHC of −485 S/cm in the four-layer thickness, and this is further enhanced to −550 S/cm with small electron doping. This AHC is seven times larger than the measured AHC in thicker 2D Fe₃GaTe₂ (178 nm). The ANC also reaches 0.55 A/K.m in the four-layer structure. Along with these, the four-layer system exhibits a large ATHC (−0.105 ~ −0.135 W/K.m). This ATHC is comparable to the large ATHC found in Weyl semimetal Co₃Sn₂S₂. Based on our results, the atomically ultrathin 2D Fe₃GaTe₂ system shows outstanding anomalous transverse conductivities and can be utilized as a potential platform for future spintronics and spin caloritronic device applications.

The performance of magnonic devices such as converters, switches, and multiplexers greatly depends on magnonic noise. While a peculiar discrete magnonic noise has been previously reported, the sources of underlying magnon dynamics occurring in high-magnon density conditions have not been clarified. Here, zero-span measurements of the spectrum analyzer were recorded to accurately detect magnonic noise as a fluctuation of the spin-wave amplitude. The results of low-frequency magnonic noise demonstrated a spin-wave mode dependency, indicating the existence of a peculiar magnon surface state. Furthermore, the energy thresholds of four-magnon scattering and autooscillation were determined using magnonic white noise. The noise data obtained in this study can help promote theoretical and experimental research on magnons.

As one of the most intractable neurological diseases, spinal cord injury (SCI) often leads to permanent neurological impairment in patients. Unfortunately, due to the complex pathological mechanisms and unique postinjury microenvironment, there is currently no way to completely repair the injured spinal cord. In recent years, with the rapid development of tissue engineering technology, the combination of biomaterials and medicine has provided a new idea for treating SCI. Here, we systematically summarize representative biomaterials, including natural, synthetic, nano, and hybrid materials, and their applications in SCI treatment. In addition, we describe several state-of-the-art fabrication techniques for tissue engineering. Importantly, we provide novel insights for the use of biomaterial-based therapeutic strategies to reduce secondary damage and promote repair. Finally, we discuss several biomaterial clinical studies. This review aims to provide a reference and new insights for the future exploration of spinal cord regeneration strategies.

As an environmentally friendly and renewable method for hydrogen production powered by solar energy, photocatalytic hydrogen evolution reactions (HERs) using broadband absorbers have received much attention. Here, we report the fabrication and characterization of an ultrabroadband absorber for the photocatalytic HER. The absorber is composed of titanium nitride and titanium dioxide heterostructures deposited onto a porous anodized aluminum oxide template. The absorber shows ultrabroadband absorption in both the visible and near-infrared regions (400–2500 nm), with averages of 99.1% and 80.1%, respectively. Additionally, the presence of the TiO₂ layer within the absorber extends the lifetime of the hot carriers by 2.7 times longer than that without the TiO₂ layer, enhancing the transfer of hot electrons and improving the efficiency of hydrogen production by 1.9 times. This novel ultrabroadband absorber has potential use in advanced photocatalytic HER applications, providing a sustainable and cost-effective route for hydrogen generation from solar energy.

The discovery of efficient magnetization switching upon device activation by spin Hall effect (SHE)-induced spin–orbit torque (SOT) changed the course of magnetic random-access memory (MRAM) research and development. However, for electronic systems with perpendicular magnetic anisotropy (PMA), the use of SOT is still hampered by the necessity of a longitudinal magnetic field to break magnetic symmetry and achieve deterministic switching. In this work, we demonstrate that robust and tunable field-free current-driven SOT switching of perpendicular magnetization can be controlled by the growth protocol in Pt-based magnetic heterostructures. We further elucidate that such growth-dependent symmetry breaking originates from the laterally tilted magnetic anisotropy of the ferromagnetic layer with PMA, a phenomenon that has been largely neglected in previous studies. We show experimentally and in simulation that in a PMA system with tilted anisotropy, the deterministic field-free switching exhibits a conventional SHE-induced damping-like torque feature, and the resulting current-induced effective field shows a nonlinear dependence on the applied current density. This relationship could be potentially misattributed to an unconventional SOT origin.

The fabrication and development of high-entropy alloys (HEAs) with exceptional functionalities is a rapidly expanding field with numerous applications. When the role of entropy in HEAs is considered, the extrinsic factors, such as the existence of grains and different phases, need to be separated from the intrinsic configurations of the atomic lattice. Here, we fabricated the CoCrFeNi₂Al_0.5 HEA/muscovite heterostructures, and some were prepared as epitaxial bilayers and others were prepared as an amorphous system. These two systems are classified into atomic-site disordered (ASD) and structurally disordered (SD) states, respectively, without the extrinsic effects for the determination of the crystal lattice role in high-entropy states. In this study, we determined the role of the structure order in correlation with the structural, electronic, and magnetic properties of HEAs using a combination of energy-dispersive X-ray spectrometry, X-ray diffraction, transmission electron microscopy, magneto-transport, ac magnetometry, and X-ray absorption spectroscopy with magnetic circular dichroism. The ASD state showed fully metallic behavior. In contrast, the SD state showed a metallic behavior with intense magnetic saturation, which was called Kondo-like behavior, under 50 K with a low-temperature coefficient of resistivity of ~64 ppm/°C. The difference between the saturation magnetic moment and the electron relaxation behavior in the ASD and SD states resulted from the existence of the structural order affecting the atomic distance and periodicity to modify the exchange interaction and tune the electron-phonon interaction for scattering. The ferromagnetic behavior contributed by Co, Fe, and Ni atoms was probed by X-ray absorption and magnetic circular dichroism to understand the magnetic interactions in the ASD and SD states.