Npg Asia Materials最新文献

{"title":"Manipulation of the magnetic monopole injection for topological transition","authors":"Hee-Sung Han, Sergio A. Montoya, Eric E. Fullerton, Weilun Chao, Soong-Geun Je, Ki‐Suk Lee, Mi-Young Im","doi":"10.1038/s41427-024-00529-9","DOIUrl":"10.1038/s41427-024-00529-9","url":null,"abstract":"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. In the nanomagnetism realm, scientists are intrigued by minuscule magnetic formations known as spin textures, possessing unique characteristics that could transform electronic devices. However, there’s a knowledge gap in controlling these structures’ transformation, especially creating stable formations called skyrmions. In a recent study, Mi-Young Im and team devised a technique to control the injection of a magnetic monopole a crucial step in forming skyrmions, in a ferrimagnetic multilayer film. They performed experiments and simulations demonstrating that a slight in-plane magnetic field can focus energy favoring MP injection, leading to skyrmion formation. The results indicated that the controlled injection of MPs is vital for the topological transition from stripe domains to skyrmions. The study concludes that the strength of the in-plane magnetic field is a critical factor in this process, offering a new method to manipulate magnetic structures for advanced technologies. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. Topological transition of a bubble to a skyrmion by the controlled magnetic monopoles injection in Fe/Gd magnetic multilayers. The magnetic monopoles injected from the top and bottom surfaces are topologically characterized by Q = −1 and Q = +1, respectively.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-10"},"PeriodicalIF":8.6,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-024-00529-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wearable respiratory sensors for health monitoring","authors":"Zhifu Yin, Yang Yang, Cong Hu, Jinzhe Li, Boyu Qin, Xue Yang","doi":"10.1038/s41427-023-00513-9","DOIUrl":"10.1038/s41427-023-00513-9","url":null,"abstract":"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. Wearable devices provide an alternative way to clinically diagnose respiratory diseases in a non-invasive and real-time manner. In this review, we summarize the recent developments in the field of wearable respiratory sensors, including the methods to synthesize various sensing materials, the ways to improve respiratory sensing performances, and the feature comparison among different sensing materials. We also summarize the concentrations, sources and associated diseases of various biomarkers in exhaled gas. Finally, we discuss current trends in the field to provide predictions for the future trajectory of wearable respiratory sensors.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-29"},"PeriodicalIF":8.6,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00513-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139753825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An advanced 3D lymphatic system for assaying human cutaneous lymphangiogenesis in a microfluidic platform","authors":"Minseop Kim, Sieun Choi, Dong-Hee Choi, Jinchul Ahn, Dain Lee, Euijeong Song, Hyun Soo Kim, Mijin Kim, Sowoong Choi, Soojung Oh, Minsuh Kim, Seok Chung, Phil June Park","doi":"10.1038/s41427-023-00527-3","DOIUrl":"10.1038/s41427-023-00527-3","url":null,"abstract":"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 fluid1,2. The skin protects our body from external stimuli such as pathogens through the cutaneous lymphatic system3,4. 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. The lymphatic system, crucial for maintaining our body’s equilibrium by eliminating waste and surplus fluid from tissues, is complex to understand, especially under unusual conditions like inflammation or tumor growth. To aid in this, researchers created a microfluidic chip model (a miniature device that simulates bodily functions) to examine lymphangiogenesis (the creation of new lymphatic vessels) in a regulated setting. This model lets scientists explore how a natural substance, Lymphanax, derived from the root of Panax Ginseng (a type of plant), impacts lymphangiogenesis. The study discovered that Lymphanax encourages the growth of new lymphatic vessels without inducing structural abnormalities, hinting at its potential medicinal value. This investigation paves the way for future study of the lymphatic system and potential treatment trials. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. The lymphatic system is essential for maintaining homeostasis of our body. Understanding the impact of environmental factors on the lymphatic system and regulating its condition are therefore crucial. We developed a microfluidic device culturing functional skin barrier and lymphatic vessel monolayer. A deep-learning algorithm was employed to validate the pro-lymphangiogenic character of a natural substance Lymphanax™, an extract of Panax Ginseng root. We foresee this platform functioning as a valuable research tool for the pharmaceutical and cosmetic industries, replacing the need for animal model","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-12"},"PeriodicalIF":8.6,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00527-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139663012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large anomalous transverse transport properties in atomically thin 2D Fe3GaTe2","authors":"Brahim Marfoua, Jisang Hong","doi":"10.1038/s41427-023-00525-5","DOIUrl":"10.1038/s41427-023-00525-5","url":null,"abstract":"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. Two-dimensional materials have become popular in science due to their unique characteristics and potential for new technologies. In this study, researchers examined a specific 2D material, Fe3GaTe2, which has shown potential due to its strong magnetism at high temperatures, making it suitable for spintronics devices that operate at room temperature or above. The team performed calculations to investigate how the thickness of Fe3GaTe2 layers impacts their magnetic and anomalous transport properties. In conclusion, the study showed that adding more layers to the Fe3GaTe2 single layer improves its anomalous transverse conductivities, which could lead to better performance in future spintronic devices. The findings suggest that ultra-thin layers of this material could be very useful in the field of spintronics, potentially leading to more efficient and powerful technology. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. We investigate the anomalous transverse conductivities of a two-dimensional (2D) magnetic Fe3GaTe2 system (monolayer to four-layer thickness). A giant anomalous thermal Hall conductivity (ATHC) of -0.14 W/K.m is obtained in the four-layer structure, and this value is comparable to the typical ATHC found in bulk materials which is rare to find in low-dimensional systems. Our findings suggest that the ultra-thin 2D Fe3GaTe2 system could be a promising platform for future spintronics and spin caloritronics device applications.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-11"},"PeriodicalIF":8.6,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00525-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139589746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mode-dependent magnonic noise","authors":"Ryo Furukawa, Shoki Nezu, Takuro Eguchi, Koji Sekiguchi","doi":"10.1038/s41427-023-00522-8","DOIUrl":"10.1038/s41427-023-00522-8","url":null,"abstract":"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. This study examines magnonic noise, a variation in spin-wave amplitude, which could offer crucial data about carrier dynamics in magnonic devices. The researchers, headed by R.F. and K.S., utilized a method known as zero-span operation of a spectrum analyser (an instrument used to examine the spectral composition of electrical, acoustic, or optical waveform) to measure magnonic noise. The study showed that magnonic noise is sensitive to both surface and internal spin-wave turbulence. They also discovered that the noise measurements permitted the direct assessment of the energy thresholds of four-magnon scattering and auto-oscillation. The findings propose that magnonic noise measurements could be a potent tool in designing future magnonic devices. The study concludes that more research is needed to detect magnonic noise at low magnon density for more efficient magnonic device design. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. Magnonic noise has unveiled magnon dynamics, including nonlinear scattering processes.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-10"},"PeriodicalIF":8.6,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00522-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139499542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomaterial-based regenerative therapeutic strategies for spinal cord injury","authors":"Keyi Chen, Wei Yu, Genjiang Zheng, Zeng Xu, Chen Yang, Yunhao Wang, Zhihao Yue, Weien Yuan, Bo Hu, Huajiang Chen","doi":"10.1038/s41427-023-00526-4","DOIUrl":"10.1038/s41427-023-00526-4","url":null,"abstract":"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. Biomaterial fabrication techniques and therapeutic strategies for spinal cord injury. This review focuses on the most recent advancements of biomaterial-based therapeutics for the treatment of spinal cord injury. The outer ring of the figure shows four fabrication techniques for tissue engineering: hydrogel, electrospinning, 3D printing and decellularization. The inner ring shows the injured spinal cord and the roles of biomaterials in spinal cord injury repair, for instance, restoring the blood‒spinal cord barrier (BSCB). Spinal cord injuries disrupt the pathways that allow the brain to communicate with the body, often resulting in paralysis and loss of sensation below the injury site. Despite advances in care, we still lack definitive treatments to fully restore function after SCI. This study focuses on the potential of biomaterials to aid in spinal cord repair. The results of these experiments have shown promise, with some materials supporting nerve growth and reducing inflammation at the injury site. However, the translation of these findings into human treatments requires further study to ensure safety and effectiveness. In conclusion, the research advances our understanding of how biomaterials can be used to promote spinal cord repair. The potential future implications of this work include the development of new treatments that could improve the quality of life for individuals with SCI. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-29"},"PeriodicalIF":8.6,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00526-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139499447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrabroadband absorptive refractory plasmonics for photocatalytic hydrogen evolution reactions","authors":"Myeongcheol Go, Inju Hong, Dasol Lee, Sanghoon Kim, Junho Jang, Keon-Woo Kim, Sangmin Shim, Kijung Yong, Junsuk Rho, Jin Kon Kim","doi":"10.1038/s41427-023-00523-7","DOIUrl":"10.1038/s41427-023-00523-7","url":null,"abstract":"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. Researchers have developed an ultrabroadband absorber for reactions that produce hydrogen using light (photocatalytic hydrogen evolution reactions), which could improve the efficiency of hydrogen production using solar energy. The team, led by M. G. and I. H., used a porous AAO template (a structure used for depositing materials), depositing TiO2 and TiN (types of chemical compounds) onto it to create a material that can absorb light across a wide spectrum. The study showed that adding the TiO2 layer increased the lifetime of hot carriers (energized particles called electrons and holes) by 2.7 times, leading to better electron transfer and improved hydrogen production efficiency. They believe this new absorber could be used for affordable hydrogen production, using environmentally friendly and renewable solar energy. Future research will explore the potential uses and scalability of this technology. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. The ultrabroadband absorptive refractory plasmonics is demonstrated with TiN and TiO2 deposited onto an anodized aluminum oxide template. The absorber shows ultrabroadband absorption in the solar spectrum (400–2500 nm). Furthermore, the absorber shows an extended hot carrier lifetime and improved efficiency of photocatalytic hydrogen production. This novel ultrabroadband absorber has great potential to provide a sustainable and cost-effective route for hydrogen generation from solar energy.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-8"},"PeriodicalIF":8.6,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00523-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139510406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The central role of tilted anisotropy for field-free spin–orbit torque switching of perpendicular magnetization","authors":"Chen-Yu Hu, Wei-De Chen, Yan-Ting Liu, Chao-Chung Huang, Chi-Feng Pai","doi":"10.1038/s41427-023-00521-9","DOIUrl":"10.1038/s41427-023-00521-9","url":null,"abstract":"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. This study explores a novel approach to achieve field-free current-driven spin–orbit torque switching of perpendicular magnetization for MRAM applications. By adjusting growth protocols in Pt-based magnetic heterostructures, a previously overlooked laterally tilted texture and magnetic anisotropy are harnessed. These findings allow deterministic switching of perpendicular magnetization without an external magnetic field. Contrary to conventional assumptions, the observed nonlinear dependence on current density resembles a damping-like torque, challenging previous notions about its origin.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-10"},"PeriodicalIF":8.6,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00521-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139459829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strain-induced specific orbital control in a Heusler alloy-based interfacial multiferroics","authors":"Jun Okabayashi, Takamasa Usami, Amran Mahfudh Yatmeidhy, Yuichi Murakami, Yu Shiratsuchi, Ryoichi Nakatani, Yoshihiro Gohda, Kohei Hamaya","doi":"10.1038/s41427-023-00524-6","DOIUrl":"10.1038/s41427-023-00524-6","url":null,"abstract":"For the development of spintronic devices, the control of magnetization by a low electric field is necessary. The microscopic origin of manipulating spins relies on the control of orbital magnetic moments (morb) by strain; this is essential for the high performance magnetoelectric (ME) effect. Herein, electric-field induced X-ray magnetic circular dichroism (XMCD) is used to determine the changes in morb by piezoelectric strain and clarify the relationship between the strain and morb in an interfacial multiferroics system with a significant ME effect; the system consists of the Heusler alloy Co2FeSi on a ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 substrate. Element-specific investigations of the orbital states by operando XMCD and the local environment via extended X-ray absorption fine structure (EXAFS) analysis show that the modulation of only the Fe sites in Co2FeSi primarily contributes to the giant ME effect. The density functional theory calculations corroborate this finding, and the growth of the high index (422) plane in Co2FeSi results in a giant ME effect. These findings elucidate the element-specific orbital control using reversible strain, called the ‘orbital elastic effect,’ and can provide guidelines for material designs with a giant ME effect. Schematic illustrations of the changes in the magnetic anisotropy by an applied electric field (E) in the strain directions are displayed. Under an applied E, the piezoelectric stress in the ferroelectric PMN-PT could be introduced in the tensile and compressive directions using positive and negative bias voltages, respectively, resulting in the changes in the magnetic anisotropy in the Co2FeSi layer. The XMCD spectra of Fe and Co L-edges in Co2FeSi under applying E showed the line shape changes only in the Fe site, which corresponds to the changes of orbital magnetic moment in Fe, while that in Co remains unchanged.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"16 1","pages":"1-10"},"PeriodicalIF":8.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00524-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of the structure order in the transport and magnetic properties of high-entropy alloy films","authors":"Jia-Wei Chen, Shih-Hsun Chen, Padraic Shafer, Wen-Yen Tzeng, Yi-Cheng Chen, Chih-Wei Luo, Wen-Wei Wu, Jien-Wei Yeh, Ying-Hao Chu","doi":"10.1038/s41427-023-00518-4","DOIUrl":"10.1038/s41427-023-00518-4","url":null,"abstract":"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 CoCrFeNi2Al0.5 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. The fabrication and development of high-entropy alloys (HEAs) with exceptional functionalities is a rapidly expanding field. The extrinsic factors, such as the existence of grains and different phases, would complicate understanding the physical phenomena. We classified the epitaxial system into atomic-site disordered (ASD) and amorphous system into structurally disordered (SD) states, respectively, to exclude the extrinsic effects of HEAs. With a comprehensive study of the magnetic and transport properties, we can further promote the research of high entropy systems.","PeriodicalId":19382,"journal":{"name":"Npg Asia Materials","volume":"15 1","pages":"1-8"},"PeriodicalIF":8.6,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41427-023-00518-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139093623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}