49 results on '"Kewen Shi"'
Search Results
2. Effects of Fe doping on structure, negative thermal expansion, and magnetic properties of antiperovskite Mn 3 GaN compounds
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Huiqing Lu, Ying Sun, Kewen Shi, Lili Wu, Ben Niu, and Cong Wang
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Materials Chemistry ,Ceramics and Composites - Published
- 2023
3. Antiferromagnetic spintronics: An overview and outlook
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Danrong Xiong, Yuhao Jiang, Kewen Shi, Ao Du, Yuxuan Yao, Zongxia Guo, Daoqian Zhu, Kaihua Cao, Shouzhong Peng, Wenlong Cai, Dapeng Zhu, and Weisheng Zhao
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Multidisciplinary - Published
- 2022
4. Effect of thermal stress on non-collinear antiferromagnetic phase transitions in antiperovskite Mn3GaN compounds with Mn3SbN inclusions
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Huimin Han, Ying Sun, Sihao Deng, Kewen Shi, Xiuliang Yuan, Jie Ren, Shihai An, Jin Cui, Dongmei Hu, Zhijie Ma, Jie Chen, Lunhua He, and Cong Wang
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Process Chemistry and Technology ,Materials Chemistry ,Ceramics and Composites ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2022
5. Spintronics intelligent devices
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Wenlong Cai, Yan Huang, Xueying Zhang, Shihong Wang, Yuanhao Pan, Jialiang Yin, Kewen Shi, and Weisheng Zhao
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General Physics and Astronomy - Published
- 2023
6. Implementation of 16 Boolean logic operations based on one basic cell of spin-transfer-torque magnetic random access memory
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Yan Huang, Kaihua Cao, Kun Zhang, Jinkai Wang, Kewen Shi, Zuolei Hao, Wenlong Cai, Ao Du, Jialiang Yin, Qing Yang, Junfeng Li, Jianfeng Gao, Chao Zhao, and Weisheng Zhao
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General Computer Science - Published
- 2023
7. Noncoplanar antiferromagnetism induced zero thermal expansion behavior in the antiperovskite Mn3Sn0.5Zn0.5Cx
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Zhijie Ma, Ying Sun, Huiqing Lu, Kewen Shi, Sihao Deng, Xiuliang Yuan, Weichang Hao, Yi Du, Yuanhua Xia, Leiming Fang, Jinbo Yang, Wenyun Yang, Claire V. Colin, Huaiming Guo, Xiaobai Ma, Dongfeng Chen, and Cong Wang
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- 2023
8. Scalable Ising Computer Based on Ultra-Fast Field-Free Spin Orbit Torque Stochastic Device with Extreme 1-Bit Quantization
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Jialiang Yin, Yu Liu, Bolin Zhang, Ao Du, Tianqi Gao, Xiangyue Ma, Yi Dong, Yue Bai, Shiyang Lu, Yudong Zhuo, Yan Huang, Wenlong Cai, Daoqian Zhu, Kewen Shi, Kaihua Cao, Deming Zhang, Lang Zeng, and Weisheng Zhao
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- 2022
9. Clinic-pathological characteristics of rare tubulointerstitial diseases
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Kewen, Shi, Shuguang, Yuan, Yao, Huang, Zheng, Li, Chang, Wang, Hong, Liu, Lin, Sun, Fuyou, Liu, and Xuejing, Zhu
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Proteinuria ,Humans ,Nephritis, Interstitial ,Immunoglobulin Light Chains ,Anemia ,Acute Kidney Injury ,Renal Insufficiency, Chronic ,Multiple Myeloma ,Hematuria - Abstract
Tubulointerstitial diseases is one of the common causes of renal dysfunction. Some rare pathological types are easy to be misdiagnosed and missedly diagnosed because of their low prevalence and relatively insufficient understanding, which affects the treatment and prognosis of patients. This study aims to explore clinical manifestations and pathological characteristics of several rare tubulointerstitial diseases, and therefore to improve their diagnosis and treatment.A total of 9 363 patients diagnosed by renal biopsy in the Department of Nephrology, Second Xiangya Hospital, Central South University from November 2011 to September 2021 were selected. Six cases of light chain cast nephropathy (LCCN), 2 cases of light chain proximal tubulopathy (LCPT), 1 case of LCCN with LCPT, 4 cases of genetic tubulointerstitial disease, and 6 cases of non-genetic related tubulointerstitial lesion were screened out, and their clinical manifestations and renal biopsy pathological results were collected, compared, and analyzed.Patients with LCCN presented with mild to moderate anemia, microscopic hematuria, and mild to moderate proteinuria. Compared with patients with LCPT, proteinuria and anemia were more prominent in patients with LCCN. Five patients with LCCN and 2 patients with LCPT had elevated serum free kappa light chain. Five patients with LCCN presented clinically with acute kidney injury (AKI). Two patients with LCPT and 1 patient with LCCN and LCPT showed CKD combined with AKI, and 1 LCPT patient presented with typical Fanconi syndrome (FS). Five patients with LCCN, 2 patients with LCPT, and 1 patient with LCCN and LCPT were diagnosed with multiple myeloma. Five patients with LCCN had kappa light chain restriction in tubules on immunofluorescence and a "fractured" protein casts with pale periodic acid-Schiff (PAS) staining on light microscopy. Immunohistochemical staining of 2 LCPT patients showed strongly positive kappa light chain staining in the proximal tubular epithelial cells. And monoclonal light chain crystals in crystalline LCPT and abnormal lysosomes and different morphological inclusion bodies in noncrystalline LCPT were observed under the electron microscope. Six patients with LCCN were mainly treated by chemotherapy. Renal function was deteriorated in 1 patient, was stable in 4 patients, and was improved in 1 patient. Two patients with LCPT improved their renal function after chemotherapy. Four patients with genetic tubulointerstitial disease were clinically presented as CKD, mostly mild proteinuria, with or without microscopic hematuria, and also presented with hyperuricemia, urine glucose under normal blood glucose, anemia, polycystic kidneys. Only 1 case had a clear family history, and the diagnosis was mainly based on renal pathological characteristics and genetic testing. Compared with patients with non-genetic related tubulointerstitial lesion, patients with genetic tubulointerstitial disease had an earlier age of onset, higher blood uric acid, lower Hb and estiated glomemlar fitration (eGFR), and less edema and hypertension. Renal pathology of genetic tubulointerstitial disease presented tubular atrophy and interstitial fibrosis, abnormal tubular dilation, glomerular capsuledilation, and glomerular capillary loop shrinkage. Glomerular dysplasia and varying degrees of glomerular sclerosis were observed. Genetic tubulointerstitial disease patients were mainly treated with enteral dialysis, hypouricemic and hypoglycemic treatment. Two genetic tubulointerstitial disease patients had significantly deteriorated renal function, and 2 patients had stable renal function.Patients with AKI or FS, who present serum immunofixation electrophoresis and/or serum free kappa light chain abnormalities, should be alert to LCCN or LCPT. Renal biopsy is a critical detection for diagnosis of LCCN and LCPT. Chemotherapy and stem cell transplantation could delay progression of renal function in patients with LCCN and LCPT. If the non-atrophic area of the renal interstitium presents glomerular capsule dilatation, glomerular capillary loop shrinkage, and abnormal tubular dilatation under the light microscopy, genetic tubulointerstitial disease might be considered, which should be traced to family history and can be diagnosed by genetic testing.
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- 2022
10. Spintronics for Energy- Efficient Computing: An Overview and Outlook
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Weisheng Zhao, Daoqian Zhu, Zongxia Guo, Yue Bai, Jialiang Yin, Kewen Shi, Kaihua Cao, and Gefei Wang
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Magnetoresistive random-access memory ,Hardware_MEMORYSTRUCTURES ,Spintronics ,business.industry ,Computer science ,Electrical engineering ,Giant magnetoresistance ,Bottleneck ,Power (physics) ,Tunnel magnetoresistance ,Torque ,Electrical and Electronic Engineering ,business ,Efficient energy use - Abstract
From the discovery of giant magnetoresistance (GMR) to tunnel magnetoresistance (TMR), their subsequent application in large capacity hard disk drives (HDDs) greatly speeded up the information era over the past decades. However, the growing demand for big-data storage and processing is limited by the von-Neumann architecture due to the memory bottleneck and power dissipation. Taking advantage of nonvolatility, high speed, and low power, magnetic random access memory (MRAM) becomes a promising candidate to overcome this limitation through processing-in-memory (PIM) architectures. In this article, we provide an overview of existing technology and give a roadmap of spintronic devices for future energy-efficient computing and its relevant integration architectures. We begin with the fundamentals of Toggle-MRAM and spin-transfer torque (STT)-MRAM, which already have commercial applications. We then introduce spin-orbit torque (SOT), a critical mechanism to realize low-power data manipulation in the next generation of MRAM and summarize the recent experimental breakthroughs of field-free SOT switching schemes. Finally, we present MRAM-based PIM architectures and novel spintronic devices, provide an application outlook, and deliver the future development potential of energy-efficient computing systems.
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- 2021
11. Mechanism of field-like torque in spin-orbit torque switching of perpendicular magnetic tunnel junction
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Yudong Zhuo, Wenlong Cai, Daoqian Zhu, Hongchao Zhang, Ao Du, Kaihua Cao, Jialiang Yin, Yan Huang, Kewen Shi, and Weisheng Zhao
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General Physics and Astronomy - Published
- 2022
12. The role of axial pre-tension in reducing energy dissipation of micro/nano-mechanical resonators
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Chengzhong Ma, Anran Wei, Kewen Shi, Yunmei Zhao, Weidong Yang, Siyu Chen, and Fenglin Guo
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Mechanics of Materials ,Mechanical Engineering ,General Physics and Astronomy ,General Materials Science - Published
- 2023
13. Sub-ns Field-Free Switching in Perpendicular Magnetic Tunnel Junctions by the Interplay of Spin Transfer and Orbit Torques
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Zongxia Guo, Jialiang Yin, Kaihua Cao, Zhaohao Wang, Zilu Wang, Daoqian Zhu, Yan Huang, Gefei Wang, Wenlong Cai, Kewen Shi, Weisheng Zhao, and Yudong Zhuo
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010302 applied physics ,Physics ,Field (physics) ,Condensed matter physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Computer Science::Hardware Architecture ,Magnetization ,0103 physical sciences ,Perpendicular ,Orbit (dynamics) ,Astrophysics::Solar and Stellar Astrophysics ,Spin transfer ,Torque ,Electrical and Electronic Engineering ,Current density ,Ultrashort pulse - Abstract
The interplay of spin-transfer torque (STT) and spin-orbit torque (SOT) highlights the potential of current-induced magnetization reversal for the ultrahigh-speed and ultralow-power memory applications. However, the ultrafast field-free switching and its dynamic mechanism have not been clarified yet. Here, we experimentally demonstrate the sub-nanosecond field-free switching by the interplay of STT and SOT in perpendicular magnetic tunnel junctions (MTJs). The dynamic investigations of the STT and SOT switching reveal that the applied SOT current can highly decrease the incubation time and current density of STT, which leads to the achievement of ultra-fast switching. Besides, the timing scheme investigations of SOT and STT pulses are performed. The firstly applied SOT current further decreases the transition time of the magnetization switching, which could result from the different nucleation and motions of domains. The interplay and the timing operations of STT and SOT provide more flexible solutions for high-speed, large-scalability and energy efficient memory applications.
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- 2021
14. Disease spectrum of 9 310 cases of renal biopsy pathological diagnosis from a single center in China
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Yao, Huang, Kewen, Shi, Xuejing, Zhu, Shuguang, Yuan, Xiaojun, Chen, Xiao, Fu, Zheng, Li, Chang, Wang, Lin, Sun, and Hong, Liu
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Adult ,China ,Adolescent ,Biopsy ,Immunoglobulins ,Glomerulonephritis, IGA ,Middle Aged ,Kidney ,Glomerulonephritis, Membranous ,Lupus Nephritis ,Young Adult ,Glomerulonephritis ,Humans ,Diabetic Nephropathies ,Aged ,Retrospective Studies - Abstract
The pathological types of renal diseases have changed in the past decade, but it lacks large sample analysis in Hunan Province. This study aims to retrospectively analyze the composition characteristics of pathological spectrum of kidney disease in Hunan Province in recent 10 years, compare the changes of pathological types of kidney disease.We collected a total of 9 310 kidney biopsy cases from 2011 to 2020 registered in the kidney biopsy system of the Nephrology Institute of the Second Xiangya Hospital of Central South University. Patients were assigned into a 14-24 years old group, a 25-44 years old group, a 45-59 years old group, and a ≥60 years old group, and divided into 2 time periods, namely 2011-2015 and 2016-2020. Pathological types of renal disease were divided into primary glomerulonephritis (PGN), secondary glomerulonephritis (SGN), tubulo-interstitial nephritis (TIN), hereditary kidney disease, and other pathological types.PGN accounted for 66.93% cases. Among PGN, IgA nephropathy (IgAN) (42.83%), membranous nephropathy (MN) (19.16%), minimal change glomerulopathy (12.46%), and focal segmental glomerulosclerosis (FSGS) (14.97%) were the 4 most common pathological types. Compared with the group in the period of 2011-2015, IgAN (46.74% vs 37.33%) and MN (21.26% vs 16.18%) were increased significantly in years 2016-2020 (bothIgAN remains the primary pathological type of kidney disease in China in the recent years. The patients with the age of 25-44 years old have the largest proportion of IgAN. With increases in age, the proportion of IgAN gradually decreases. MN increases to different degrees at various ages, while cases of HT, DN, and monoclonal immunoglobulin-related renal damage have increased. This single-center renal pathology spectrum can provide clinical evidence for diagnosis, prevention and epidemiological study.
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- 2022
15. Discovery of negative thermal expansion with giant thermal hysteresis in Fe3NiBx
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Kewen Shi, Rongjin Huang, Xiuliang Yuan, Jin Cui, Cong Wang, Ying Sun, and Laifeng Li
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010302 applied physics ,Diffraction ,Thermal hysteresis ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,Crystal structure ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Condensed Matter::Materials Science ,Magnetization ,chemistry ,Negative thermal expansion ,Mechanics of Materials ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,Boron - Abstract
Negative thermal expansion (NTE) behavior with giant thermal hysteresis exceeding 450 K has been observed in Fe3NiBx. This behavior is desirable in the field of pipe joint or encapsulation. The temperature dependent X-ray diffraction and magnetization indicate that NTE behavior with giant thermal hysteresis is related to crystal structure transition between face-centered cubic (fcc) and body-centered cubic (bcc), but not to the magnetic transition. The introduction of boron can reduce the NTE temperature range and stabilize the high temperature fcc phase. Therefore, we can obtain the NTE behavior below room temperature during cooling process, which is important for the practical application.
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- 2020
16. Sign Change of Spin-Orbit Torque in Pt/NiO/CoFeB Structures
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Dapeng Zhu, Tianrui Zhang, Xiao Fu, Runrun Hao, Amir Hamzić, Huaiwen Yang, Xueying Zhang, Hui Zhang, Ao Du, Danrong Xiong, Kewen Shi, Shishen Yan, Shufeng Zhang, Albert Fert, and Weisheng Zhao
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spintronics, spin torque, spin current, antiferromagnets, magnetic multilayers ,General Physics and Astronomy - Abstract
Antiferromagnetic insulators have recently been proved to support spin current efficiently. Here, we report the damping-like spin- orbit torque (SOT) in Pt / NiO / CoFeB has a strong temperature dependence and reverses the sign below certain temperatures, which is different from the slight variation with temperature in the Pt / CoFeB bilayer. The negative damping-like SOT at low temperatures is proposed to be mediated by the magnetic interactions that tie with the “exchange bias” in Pt / NiO / CoFeB, in contrast to the thermal-magnon-mediated scenario at high temperatures. Our results highlight the promise to control the SOT through tuning the magnetic structure in multilayers.
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- 2022
17. Femtosecond laser-assisted switching in perpendicular magnetic tunnel junctions with double-interface free layer
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Luding Wang, Wenlong Cai, Kewen Shi, Kaihua Cao, B Bert Koopmans, Weisheng Zhao, Physics of Nanostructures, EIRES, and Eindhoven Hendrik Casimir institute
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spintronics ,Materials science ,General Computer Science ,Spintronics ,business.industry ,Demagnetizing field ,Magnetic storage ,magnetic tunnel junctions (MTJs) ,Laser ,heat-assisted magnetic recording (HAMR) ,Magnetic field ,law.invention ,Tunnel magnetoresistance ,femtosecond laser ,law ,thermally-assisted switching (TAS) ,Computer data storage ,Femtosecond ,Optoelectronics ,business - Abstract
Perpendicular magnetic tunnel junctions with double-interface free layer (p-DMTJs), which exhibit enhanced tunnel magnetoresistance (TMR) and thermal stability (Δ) at the nanoscale, have received considerable interest as building blocks for spintronic data storage devices. Heat-assisted magnetic recording (HAMR) techniques have been widely employed in mainstream magnetic storage to enable ultrahigh storage density. However, the data access is achieved by sensing the stray field of the selected magnetic element using a mechanical “read head”, resulting in an unfavorable speed limitation and design complexity. To address this issue, integrating laser-assisted switching with a high-performance magnetic tunnel junction has received interest in spintronic R&D; however, it has not yet been achieved. In this study, we experimentally explored femtosecond (fs) laser-assisted switching in a p-DMTJ device using a direct electrical TMR readout. We demonstrate two reconfigurable switching operations, i.e., binary “write” and unidirectional “reset”, by the interplay of the fs laser and synchronized magnetic field sequence. We further explored the joint effect, and a switching phase diagram was obtained. The effect of the stray field of p-DMTJ, as well as laser helicity, on switching is also discussed. Results show the feasibility of fs laser-assisted writing p-DMTJs, which can pave the way in high-density optospintronic storage applications.
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- 2021
18. Sign reversal of the anomalous Hall effect in antiperovskite (110)-oriented Mn3.19Ga0.81N1−δ film
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Huimin Han, Ying Sun, Kewen Shi, Xiuliang Yuan, Jie Ren, Jin Cui, Dongmei Hu, Kaiqi Zhang, and Cong Wang
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General Physics and Astronomy - Abstract
Antiperovskite compounds with abundant magnetic phase transitions provide an ideal platform for exploring nontrivial magnetotransport responses. In this study, the anomalous Hall effect (AHE) in an antiperovskite (110)-oriented Mn3.19Ga0.81N1−δ film up to room temperature was observed, and an unusual sign reversal was detected in the Hall measurements. The AHE reversal suggests that the carrier reversal corresponds to a magnetic transition from a ferrimagnetic order to noncollinear antiferromagnetic order at about 240 K. Analysis of the scaling relation of AHE indicates that the sign reversal originates from the transition from the skew scattering dominated AHE to the intrinsic mechanism dominated AHE. These findings will inspire effective control of the magnetic configuration and innovative applications for manipulating carrier transport in spintronic memory devices based on antiperovskite films.
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- 2022
19. Design of negative/nearly zero thermal expansion behavior over a wide temperature range by multi-phase composite
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Kewen Shi, Ping Song, Huaiming Guo, Huimin Han, Rongjin Huang, Jin Cui, Laifeng Li, Shihai An, Xiuliang Yuan, Cong Wang, and Ying Sun
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Materials science ,Intermetallics ,Multi phase ,Composite number ,02 engineering and technology ,Negative/nearly zero thermal expansion ,010402 general chemistry ,01 natural sciences ,Thermal expansion ,Negative thermal expansion ,lcsh:TA401-492 ,General Materials Science ,Composite material ,Composites ,Mechanical Engineering ,Zero (complex analysis) ,Mn-based anti-perovskites ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Mechanics of Materials ,Volume fraction ,lcsh:Materials of engineering and construction. Mechanics of materials ,0210 nano-technology ,Stability ,Metallic bonding - Abstract
The negative thermal expansion (NTE) or nearly zero thermal expansion (NZTE) behaviors have been found in some magnetic metallic compounds with great application prospects. However, it is a big challenge for applications that the responding temperature range is not broad enough or far away from room temperature. Herein, a new method is put forward to design the wide temperature range of NTE and NZTE Behavior by NTE/NZTE multi-phase composite. In this method, the optimized volume fraction of the components achieves a concordant collaboration of multi-phase in the counteraction of NTE and positive thermal expansion (PTE) at several adjacent temperature ranges and thus the temperature range is broadened as expected. By this method, MnCuGeN-based NTE composite (290 K ≤ T ≤ 385 K, ΔT = 95 K) and MnCuZnSiGeN-based NZTE composite (200 K ≤ T ≤ 400 K, ΔT = 200 K) with excellent stability have been successfully designed and prepared. This idea will open an avenue to the multi-phase composite with designable NTE/NZTE properties, which would have important applications in aerospace and other modern industries.
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- 2021
20. Effective Cultivation of Cross-Border E-Commerce Talents via Virtual Communities of Practice with Multi-media, Multi-layered WeChat Groups
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Yulu Wang, Lin Su, Ying Lu, Xiaoli Shen, Hailun Wang, Kewen Shi, Yuhui Pan, Wen Zhou, and Ping Liu
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Structure (mathematical logic) ,Knowledge management ,Virtual community of practice ,Computer science ,business.industry ,media_common.quotation_subject ,International business ,E-commerce ,Product (category theory) ,business ,Function (engineering) ,media_common - Abstract
Cross-Border eCommerce (CBeC) is now one of the most dynamic and important phenomena in international business, and the cultivation of talents in this area has become a pressing issue. This paper discusses our experiments in which a Virtual Community of Practice (VCoP) with multi-media, multi-layered WeChat groups was established. Results show that this VCoP has been proved both suitable and effective: it solved the problem of multi-location of participants in this programme by setting up a convenient and almost free-of-charge VCoP; the structure of 3-layered WeChat groups has been both efficient and effective, with students concentrating on the specific product and function in which they specialize; and the use of multi-media functions available on the WeChat platform for lecture delivery and discussion has improved the teaching effects and motivated students in learning and practice.
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- 2021
21. Modulation of field-like spin orbit torque in heavy metal/ferromagnet heterostructures
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Houyi Cheng, Albert Fert, Weisheng Zhao, Zilu Wang, Jie Zhang, Daoqian Zhu, Junfeng Qiao, Kewen Shi, Dapeng Zhu, Sylvain Eimer, Wenlong Cai, Xueying Zhang, and Yang Liu
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Magnetoresistive random-access memory ,Materials science ,Condensed matter physics ,Magnetoresistance ,Annealing (metallurgy) ,Conductance ,Heterojunction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferromagnetism ,0103 physical sciences ,Torque ,General Materials Science ,010306 general physics ,0210 nano-technology ,Ultrashort pulse - Abstract
Spin orbit torque (SOT) has drawn widespread attention in the emerging field of magnetic memory devices, such as magnetic random access memory (MRAM). To promote the performance of SOT-MRAM, most efforts have been devoted to enhance the SOT switching efficiency by improving the damping-like torque. Recently, some studies noted that the field-like torque also plays a crucial role in the nanosecond-timescale SOT dynamics. However, there is not yet an effective way to tune its relative amplitude. Here, we experimentally modulate the field-like SOT in W/CoFeB/MgO trilayers through tuning the interfacial spin accumulation. By performing spin Hall magnetoresistance measurement, we find that the CoFeB with enhanced spin dephasing, either generated from larger layer thickness or from proper annealing, can distinctly boost the spin absorption and enhance the interfacial spin mixing conductance Gr. While the damping-like torque efficiency increases with Gr, the field-like torque efficiency is found to decrease with it. The results suggest that the interfacial spin accumulation, which largely contributes to the field-like torque, is reduced by higher interfacial spin transparency. Our work shows a new path to further improve the performance of SOT-based ultrafast magnetic devices.
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- 2020
22. The influence of combination of the first-order and second-order phase transitions on magnetocaloric effects in Mn3Cu1-xFexN
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Cong Wang, Wenjun Zhao, Yunlin Chen, Jun Yan, Huiqing Lu, Ying Sun, Kewen Shi, and Sihao Deng
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Phase transition ,Materials science ,Condensed matter physics ,Doping ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,First order ,Cooling capacity ,01 natural sciences ,Antiperovskite ,Order (biology) ,Phase (matter) ,0103 physical sciences ,Materials Chemistry ,Magnetic refrigeration ,010306 general physics ,0210 nano-technology - Abstract
The influences of Fe substitutions on magnetic properties, phase transformations and magnetocaloric effects of Mn3Cu1-xFexN have been investigated. The magnetic phase transition temperature (Tc) increases but the first-order phase transition temperature decreases with increasing the Fe content. Fe doping separates the first-order phase transition into first-order and second-order phase transitions in Mn3Cu1-xFexN. The second-order (paramagnetic-ferromagnetic) transition coexists with first-order (ferromagnetic-ferrimagnetic) transition in Mn3Cu0.95Fe0.05N. Introduction of the second-order magnetic transition broadens the phase transition span, which greatly enhances the relative cooling power of Mn3CuN. The results indicate that resolving complex magnetic phase transition may improve the cooling capacity of antiperovskite compounds.
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- 2018
23. Effects of Ni substitution on magnetism and thermal expansion of antiperovskite Mn3Ga1-xNixN (0 ≤ x ≤ 1.0)
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Lei Wang, Kewen Shi, Cong Wang, Rongjing Huang, Xiuliang Yuan, Wei Wang, Jun Yan, Huiqing Lu, Xungang Diao, and Ying Sun
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010302 applied physics ,Materials science ,Condensed matter physics ,Magnetic structure ,Magnetism ,Process Chemistry and Technology ,Doping ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Thermal expansion ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Antiperovskite ,Ferromagnetism ,Lattice (order) ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,Antiferromagnetism ,0210 nano-technology - Abstract
Effects of Ni substitution on magnetic and thermal expansion properties in Mn 3 Ga 1−x Ni x N (0 ≤ x ≤ 1.0) were investigated. The magnetic structure for Mn 3 GaN is a typical noncollinear antiferromagnetic Γ 5 g . After Ni was introduced to the Ga site, the spin alignment was changed from antiferromagnetic to ferromagnetic. In addition, the magnetic transition temperature first decreased and then increased with increasing Ni content, which could be ascribed to the competition between the electron-type doping effect and the lattice effect. Near the magnetic transition, Mn 3 Ga 1−x Ni x N showed an abrupt lattice contraction with increasing temperature and the magnitude of the lattice contraction gradually decreased from 0.38% (for x = 0) to 0.09% (for x = 1.0) with increasing Ni substitution. In particular, zero thermal expansion behavior below 150 K was observed in Mn 3 Ga .6 Ni .4 N, and thermal expansion coefficient α was estimated to be 0.311 × 10 −6 K −1 . The obtained zero thermal expansion is very useful for practical applications in precision devices. The zero thermal expansion behavior was assumed to be associated with the ferromagnetic characteristic induced by the Ni substitution, which stabilized the Γ 5 g antiferromagnetic structure.
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- 2018
24. Phase separation and zero thermal expansion in antiperovskite Mn3Zn0.77Mn0.19N0.94: An in situ neutron diffraction investigation
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Hui Wu, Pengwei Hu, Sihao Deng, Christoph Sürgers, Xungang Diao, Jun Yan, Cong Wang, Zaixing Shi, Kewen Shi, Qingzhen Huang, Lei Wang, and Ying Sun
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010302 applied physics ,In situ ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Neutron diffraction ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Thermal expansion ,Antiperovskite ,Mechanics of Materials ,Ferrimagnetism ,Lattice (order) ,Phase (matter) ,0103 physical sciences ,Antiferromagnetism ,General Materials Science ,0210 nano-technology - Abstract
The antiperovskite Mn 3 Zn 0.77 Mn 0.19 N 0.94 was investigated by in situ neutron powder diffraction (NPD) in the temperature region 5–300 K. Here, a noncollinear-antiferromagnetic/collinear-ferrimagnetic phase separation (PS) showing different lattice parameters was firstly revealed in antiperovskites. The NPD results prove that the noncollinear antiferromagnetic phase, even coexisting with the collinear ferrimagnetic phase, could be responsible for the zero thermal expansion behavior of Mn 3 Zn 0.77 Mn 0.19 N 0.94 below 110 K. These findings suggest that Mn 3 ZnN based materials could open a new avenue for further exploring the noncollinear magnetic PS and correlated physical properties of antiperovskites.
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- 2018
25. Tunable negative thermal expansion and structural evolution in antiperovskite Mn3 Ga1−x Ge x N (0 ≤ x ≤ 1.0)
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Cong Wang, Huiqing Lu, Sihao Deng, Ying Sun, Lei Wang, Huimin Han, Shenghua Deng, Wenjun Zhao, and Kewen Shi
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010302 applied physics ,Diffraction ,Materials science ,Analytical chemistry ,02 engineering and technology ,Crystal structure ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structural evolution ,Thermal expansion ,Antiperovskite ,Tetragonal crystal system ,Negative thermal expansion ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,0210 nano-technology - Abstract
The negative thermal expansion (NTE) and structural evolution of antiperovskite compounds Mn3Ga1−xGexN (0 ≤ x ≤ 1.0) were systematically investigated. Our results indicate the crystal structure of Mn3Ga1−xGexN changes from cubic (C) to tetragonal (T4) with increasing Ge content by X-ray diffraction (XRD).The negative thermal expansion from x = 0 (operation-temperature range ▵T = 20 K) to x = 0.4 (▵T = 60 K) becomes broad and shifts to higher temperature, and then it became positive from x = 0.5 in Mn3Ga1−xGexN. Typically, Mn3Ga0.5Ge0.5N shows low thermal expansion behavior between 300 and 450 K (∆T = 150 K), and thermal expansion coefficient α is estimated to be 2 × 10−6 K−1. Furthermore, variable temperature XRD was measured to reveal the origin of NTE. The cubic I - cubic II phases coexistence (x = 0.2) and cubic I - tetragonal coexistence (x = 0.5, 0.6) was observed at low temperature. The tunable NTE is highly valuable for practical applications in precision devices.
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- 2017
26. Rectifying Characteristics and Semiconductor–Metal Transition Induced by Interfacial Potential in the Mn3CuN/n-Si Intermetallic Heterojunction
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Sihao Deng, Lei Wang, Huiqing Lu, Pengwei Hu, Weihua Tang, Cong Wang, Kewen Shi, Tianmin Wang, Weichang Hao, and Ying Sun
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Materials science ,business.industry ,Intermetallic ,Schottky diode ,Heterojunction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Antiperovskite ,Band bending ,Semiconductor ,Rectification ,0103 physical sciences ,Optoelectronics ,General Materials Science ,010306 general physics ,0210 nano-technology ,business ,Voltage - Abstract
The Mn3CuN/n-Si heterojunction device is first designed in the antiperovskite compound, and excellent rectifying characteristics are obtained. The rectification ratio (RR) reaches as large as 38.9 at 10 V, and the open-circuit voltage Voc of 1.13 V is observed under temperature of 410 K. The rectifying behaviors can be well described by the Shockley equation, indicating the existence of a Schottky diode. Simultaneously, a particular semiconductor–metal transition (SMT) behavior at 250 K is also observed in the Mn3CuN/n-Si heterojunction. The interfacial band bending induced inversion layer, which is clarified by the interfacial schematic band diagrams, is believed to be responsible for the SMT and rectifying effects. This study can develop a new class of materials for heterojunction, rectifying devices, and SMT behaviors.
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- 2017
27. Ultra-low power consumption Spintronics Devices
- Author
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Kaihua Cao, Weisheng Zhao, Zongxia Guo, and Kewen Shi
- Subjects
Ultra low power ,Magnetoresistive random-access memory ,Hardware_MEMORYSTRUCTURES ,Spintronics ,Computer science ,Spin-transfer torque ,Integrated circuit ,Engineering physics ,law.invention ,Reliability (semiconductor) ,Hardware_GENERAL ,law ,Power consumption ,Hardware_ARITHMETICANDLOGICSTRUCTURES ,Electronic circuit - Abstract
Spintronics devices has attracted considerable interest and attention, especially for the magnetic random-access memories (MRAMs), which have high reliability, low power consumption and fast operation speed. Remarkable progress in innovative materials and new circuits structures in spintronics have been witnessed. This paper reviews our researches of ultra-low power consumption spintronics devices reported in recent years. Both the highly efficient spin transfer torque (STT) MRAM and the filed-free spin orbit torque (SOT) MRAM are discussed. Based on these spintronics devices, the NAND-like spintronics memory (NAND-SPIN) structure and in-memory processing method give the potential solutions for next generation integrated circuits.
- Published
- 2019
28. All Perpendicular Spin Nano-Oscillators with Composite Free Layer
- Author
-
Kaihua Cao, Jiaqi Wei, Chao Zhao, Hushan Cui, Huisong Li, Kewen Shi, Wenlong Cai, Weisheng Zhao, and Yang Jing
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Perpendicular magnetic anisotropy ,Composite number ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Tunnel magnetoresistance ,0103 physical sciences ,Nano ,Perpendicular ,Thermal stability ,Electrical and Electronic Engineering ,0210 nano-technology ,Layer (electronics) ,Spin-½ - Abstract
Owing to improved thermal stability and scalability, materials with perpendicular magnetic anisotropy (PMA) are extremely attractive. The all perpendicular magnetic tunnel junction ([Formula: see text]-MTJ) devices are primarily devoted to spin transfer torque (STT)-induced switching and few works report their microwave emission. Here, we demonstrate the basic results of RF function in nanoscale [Formula: see text]-MTJ which has two different thickness free layers separated by atom-thick tungsten insertion. The ultrathin W spacer layer not only enables the two CoFeB free layers precess as a single layer but also greatly enhances the PMA which further induces high-emission frequency. The all perpendicular spin transfer torque nano-oscillator (STNO) exhibited high frequency (7.6[Formula: see text]GHz) and large current modulation capability of [Formula: see text] at moderate external magnetic field. Along with our previous work on STT switching utilizing the similar stack, such a multifunctional structure could bring low cost solutions to Internet of Things (IoT) network applications.
- Published
- 2019
29. Giant zero-field cooling exchange-bias-like behavior in antiperovskite Mn3Co0.61Mn0.39N compound
- Author
-
Hui Wu, Weichang Hao, Sihao Deng, Qingzhen Huang, Zhiyong Mao, Ping Song, Cong Wang, Kewen Shi, Ying Sun, Pengwei Hu, Lei Wang, and Shenghua Deng
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Magnetic moment ,Magnetic structure ,Lattice (group) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Coupling (probability) ,01 natural sciences ,Antiperovskite ,Magnetization ,Crystallography ,Exchange bias ,0103 physical sciences ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,010306 general physics ,0210 nano-technology - Abstract
Giant zero-field cooling exchange-bias-like behavior with ${H}_{\mathrm{EB}}=3.49\phantom{\rule{0.16em}{0ex}}\mathrm{kOe}$ was found in an antiperovskite $\mathrm{M}{\mathrm{n}}_{3}\mathrm{C}{\mathrm{o}}_{0.61}\mathrm{M}{\mathrm{n}}_{0.39}\mathrm{N}$ compound. The magnetic structure of $\mathrm{M}{\mathrm{n}}_{3}\mathrm{C}{\mathrm{o}}_{0.61}\mathrm{M}{\mathrm{n}}_{0.39}\mathrm{N}$ was resolved to be ferrimagentic ordering composed of canted ${\mathrm{\ensuremath{\Gamma}}}^{5\mathrm{g}}$ antiferromagnetic (AFM) and ferromagnetic (FM) along the [111] direction by the neutron diffraction technique. The exchange coupling model was proposed together with the first principles calculation for further understanding this exchange-bias-like behavior. It was found that the ferromagnetic exchange interaction between FM and the canted ${\mathrm{\ensuremath{\Gamma}}}^{5\mathrm{g}}$ AFM play an important role in the particular exchange-bias-like behavior. The exchange coupling constructed in the lattice is distinct from the interactions between collinear AFM and FM in conventional exchange bias system. In addition to the enhanced horizontal shift, hysteresis loops obtained after FC cooling also exhibited vertical shift. The macroscopic vertical shift of the magnetization is ascribed to the increase of the magnetic moment of canted ${\mathrm{\ensuremath{\Gamma}}}^{5\mathrm{g}}$ spins along the external magnetic field. This finding will promote the development of advanced magnetic devices.
- Published
- 2019
30. Fully Dense Mn 3Zn 0.7Ge 0.3N /Al Composites with Zero Thermal Expansion Behavior Around Room Temperature
- Author
-
Qiang Zhang, Cong Wang, Kewen Shi, Gaohui Wu, Chang Zhou, Sihao Deng, and Xin Tan
- Subjects
Mechanical property ,Materials science ,Composite number ,Electronic packaging ,Zero (complex analysis) ,Modulus ,Composite material ,Infiltration (HVAC) ,Thermal expansion - Abstract
The fully dense, low-reacted Mn3Zn0.7Ge0.3N/Al composites were successfully fabricated by pressure infiltration technology. The large positive thermal expansion of Al is effectively suppressed by adding Mn3Zn0.7Ge0.3N component. Nearly zero thermal expansion (α=-0.41×10-6K-1) is achieved between 35 and 70°C in the composite with 30vol.% Mn3Zn0.7Ge0.3N. Moreover, the bending stress and modulus of Mn3Zn0.7Ge0.3N/Al composites increase gradually with increasing Mn3Zn0.7Ge0.3N content. This low thermal expansion, good mechanical properties materials is beneficial to electronic packaging and precision field.
- Published
- 2019
31. Large negative thermal expansion provided by metal-organic framework MOF-5: A first-principles study
- Author
-
Sihao Deng, Cong Wang, Huiqing Lu, Ying Sun, Lei Wang, and Kewen Shi
- Subjects
Bulk modulus ,Materials science ,Phonon ,Nanoporous ,Thermodynamics ,02 engineering and technology ,Grüneisen parameter ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Negative thermal expansion ,chemistry ,Molecular vibration ,Physical chemistry ,General Materials Science ,Density functional theory ,Carboxylate ,0210 nano-technology - Abstract
The thermodynamic properties and negative thermal expansion (NTE) behavior of metal-organic framework MOF-5 are investigated within the quasi-harmonic approximation, by using density functional theory. For nanoporous MOF-5, the temperature dependence of bulk modulus increases with increasing temperature, indicating that the resistance to compression is enhanced gradually. The large NTE behavior is obtained, which agrees reasonably with the experimental data. From the Gruneisen parameter as a function of temperature, it can be found that low-frequency phonons are closely associated with the NTE of MOF-5. The corresponding vibrational modes can be viewed as the results of local deformations (translation, rotation, twisting) of BDC (1,4-benzenedicarboxylate) linker and zinc clusters. The lowest-frequency phonon mode (the transverse motion of carboxylate groups and benzene ring, zinc clusters being as rigid units) is confirmed to be most responsible for thermal contraction.
- Published
- 2016
32. Effects of Cr-doping on the electronic transport properties in antiperovskite nitrides Mn3−xCrxZnN (0≤x≤0.5)
- Author
-
Kewen Shi, Ying Sun, Muhammad Imran Malik, Sihao Deng, Huiqing Lu, Lei Wang, Cong Wang, and Pengwei Hu
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Doping ,Intermetallic ,02 engineering and technology ,Activation energy ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Polaron ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Residual resistivity ,Magnetization ,Antiperovskite ,Electrical resistivity and conductivity ,0103 physical sciences ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
Antiperovskite intermetallic Mn3−xCrxZnN (0≤x≤0.5) compounds have been prepared to study the Cr doping effect on the electronic transport properties. The temperature dependent resistivity ρ(T) for x≤0.3 shows notable and broader slope change. Meanwhile, with increasing Cr doping, the slope change shifts to lower temperatures and is gradually suppressed for x>0.3. For x=0.0 and 0.5, the measurements of magnetization from 10 K to 350 K reveal that Mn3−xCrxZnN compounds go through a transition from the dominant AFM interactions to one where the FM and AFM interactions coexist. For low-temperature region (15–80 K), the electron–electron scattering is dominant, and the number of phonons abruptly increases with increasing temperature. Small polaron hopping model (SPH) is used to understand the temperature dependence of electrical resistivity in the high-temperature range of 200–300 K and a clear decrease of the polaron activation energy was observed for x≤0.2. The residual resistivity ratio (RRR) decreases while the residual resistivity increases (ρ0) with increasing Cr-doping level. The maximum total entropy change (ΔSmax) decreases by increasing the Cr doping from x=0.0 to 0.2.
- Published
- 2016
33. Competition between ferromagnetic and antiferromagnetic interactions by Cr doping at Mn sites in antiperovskite Mn 3−x Cr x ZnN (0≤ x ≤0.5) compounds
- Author
-
Sihao Deng, Huiqing Lu, Ying Sun, Muhammad Imran Malik, Cong Wang, Lei Wang, Pengwei Hu, and Kewen Shi
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Intermetallic ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Magnetic hysteresis ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Antiperovskite ,Magnetization ,Lattice constant ,chemistry ,Ferromagnetism ,0103 physical sciences ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Electrical and Electronic Engineering ,0210 nano-technology ,AFm phase - Abstract
The Cr doping effect on the lattice and magnetic properties in Mn3−xCrxZnN was reported in the antiferromagnetic intermetallic host material Mn3ZnN. The lattice parameter decreases with the increase of the Cr concentration. Measurements of magnetization from 10 K to 350 K reveal that sharp antiferromagnetic (AFM)-to-paramagnetic (PM) transitions of the host material exist at 185 K (ZFC) and 177 K (FC). The peak is broadened clearly as the Cr doping was increased and when the Cr concentration exceeded 0.3, a significant ferromagnetic (FM) character was found to coexist with an AFM phase. At x=0.4 and 0.5, the M–H curves exhibit small magnetic hysteresis loop, indicating the dominant FM interactions in these samples. Also, a positive value of Weiss Temperature (ΘW) at x=0.5 in H/M–T plot suggests that the FM interaction is dominant when the Cr doping increases.
- Published
- 2016
34. The evolution of magnetic transitions, negative thermal expansion and unusual electronic transport properties in Mn3AgxMnyN
- Author
-
Kewen Shi, Lei Wang, Pengwei Hu, Jun Yan, Zaixing Shi, Sihao Deng, Muhammad Imran Malik, Cong Wang, and Ying Sun
- Subjects
Materials science ,Condensed matter physics ,Scattering ,chemistry.chemical_element ,General Chemistry ,Manganese ,Nitride ,Condensed Matter Physics ,Magnetic transitions ,Antiperovskite ,chemistry ,Negative thermal expansion ,Electrical resistivity and conductivity ,Materials Chemistry ,Néel temperature - Abstract
The antiperovskite compounds Mn 3 Ag x Mn y N with Ag vacancies and Mn doping at Ag site were synthesized and investigated. The introduction of Ag vacancies has a very small influence on magnetic transitions. However, the magnetic transitions at T N (Neel temperature) and T t (transition at lower temperature) gradually overlap with Mn doping accompanied by broadening of negative thermal expansion behavior. We also observed the nearly zero temperature coefficient of resistivity (NZ-TCR) behavior above magnetic order–disorder transition. The tunable TCR values from positive to negative could be achieved in Mn 3 Ag x Mn y N by reducing the contribution of (electron–phonon) e–p scattering in resistivity. Our results reveal the significance of e–p scattering for the evolution of TCR values, which could enrich the understanding of NZ-TCR behavior in antiperovskite manganese nitrides.
- Published
- 2015
35. Giant Perpendicular Magnetic Anisotropy in Mo‐Based Double‐Interface Free Layer Structure for Advanced Magnetic Tunnel Junctions
- Author
-
Boyu Zhang, Weisheng Zhao, Shouzhong Peng, Zilu Wang, Daoqian Zhu, Yong Xu, Kewen Shi, Jingle Chen, Kaihua Cao, Sylvain Eimer, Xinran Wang, Danrong Xiong, Zongxia Guo, and Houyi Cheng
- Subjects
Materials science ,Condensed matter physics ,Interface (Java) ,Perpendicular magnetic anisotropy ,Layer (electronics) ,Electronic, Optical and Magnetic Materials - Published
- 2020
36. Investigation of the spin-lattice coupling in Mn3Ga1−xSnxN antiperovskites
- Author
-
Sihao Deng, Lei Wang, Jun Yan, Huiqing Lu, Pierre Bordet, Yamaura Kazunari, Claire V. Colin, Wenjun Zhao, Cong Wang, Ying Sun, and Kewen Shi
- Subjects
Physics ,Magnetic structure ,Magnetic moment ,02 engineering and technology ,Atmospheric temperature range ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Coupling (probability) ,01 natural sciences ,Omega ,0104 chemical sciences ,Crystallography ,Antiperovskite ,Content (measure theory) ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology - Abstract
The magnetovolume effects (MVEs) of $\mathrm{M}{\mathrm{n}}_{3}\mathrm{G}{\mathrm{a}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{n}}_{x}\mathrm{N}$ antiperovskite compounds have been investigated by means of neutron powder diffraction. Increasing the Sn-doping content at the Ga site leads to the broadening of the magnetic phase transition temperature range and the thermal expansion behavior changes from negative to positive. We establish the relationship between the square of the ordered magnetic moment ${m}^{2}$ and the volume variation $\mathrm{\ensuremath{\Delta}}{\ensuremath{\omega}}_{m}$ for the antiferromagnetic phase (${\mathrm{\ensuremath{\Gamma}}}^{5g}$ magnetic structure with rhombohedral symmetry $R\overline{3}m$). The temperature variations of $\mathrm{\ensuremath{\Delta}}{\ensuremath{\omega}}_{m}(T), {m}^{2}(T)$ and the magnetoelastic coupling constant $C(T)$ are also quantitatively analyzed according to the itinerant-electron theory. Moreover, the increase of the phonon contribution to the thermal expansion induced by Sn doping and the corresponding decrease of dm/dT are revealed to be the key parameters for tuning the MVEs. Our results allow elucidating and quantifying the mechanism of the spin-lattice coupling and can be used to design magnetic functional materials with controlled thermal expansion behaviors for specific applications.
- Published
- 2018
37. Negative Thermal Expansion over a Wide Temperature Range in Fe-Doped MnNiGe Composites
- Author
-
Lei Wang, Huiqing Lu, Ping Song, Xiuliang Yuan, Yufei Liu, Wenjun Zhao, Ying Sun, Huimin Han, Cong Wang, and Kewen Shi
- Subjects
Work (thermodynamics) ,magnetic transition ,Materials science ,Analytical chemistry ,Absolute value ,02 engineering and technology ,010402 general chemistry ,composites ,01 natural sciences ,Thermal expansion ,lcsh:Chemistry ,Metal ,Negative thermal expansion ,Original Research ,General Chemistry ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,negative thermal expansion ,Chemistry ,lcsh:QD1-999 ,Ferromagnetism ,Fe doped ,visual_art ,Heusler alloys ,visual_art.visual_art_medium ,Fe-Doped MnNiGe ,0210 nano-technology - Abstract
Fe-doped MnNiGe alloys were successfully synthesized by solid-state reaction. Giant negative thermal expansion (NTE) behaviors with the coefficients of thermal expansion (CTE) of −285.23 × 10−6 K−1 (192–305 K) and −1167.09 × 10−6 K−1 (246–305 K) have been obtained in Mn0.90Fe0.10NiGe and MnNi0.90Fe0.10Ge, respectively. Furthermore, these materials were combined with Cu in order to control the NTE properties. The results indicate that the absolute value of CTE gradually decreases with increasing Cu contents. In Mn0.92Fe0.08NiGe/x%Cu, the CTE gradually changes from −64.92 × 10−6 K−1 (125–274 K) to −4.73 × 10−6 K−1 (173–229 K) with increasing value of x from 15 to 70. The magnetic measurements reveal that the NTE behaviors in this work are strongly correlated with the process of the magnetic phase transition and the introduction of Fe atoms could also change the spiral anti-ferromagnetic (s-AFM) state into ferromagnetic (FM) state at low temperature. Our study launches a new candidate for controlling thermal expansion properties of metal matrix materials which could have potential application in variable temperature environment.
- Published
- 2018
38. Frustrated Triangular Magnetic Structures of Mn3ZnN: Applications in Thermal Expansion
- Author
-
Ying Sun, Jun Yan, Sihao Deng, Qingzhen Huang, Lei Wang, Hui Wu, Cong Wang, Kewen Shi, Zaixing Shi, Pengwei Hu, and Ali Zaoui
- Subjects
Materials science ,Magnetic structure ,Condensed matter physics ,Magnetism ,Doping ,Thermal expansion ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Antiperovskite ,General Energy ,Negative thermal expansion ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Physical and Theoretical Chemistry ,Ground state - Abstract
One of the specific subjects in frustrated magnetic systems is the phenomenon coupled with noncollinear magnetism, such as zero or negative thermal expansion (ZTE or NTE) in antiperovskite compounds. The first-principles calculations and neutron powder diffraction (NPD) are used to reveal the control of the noncollinear Γ5g antiferromagnetic (AFM) structure and corresponding thermal expansion properties in Mn3Zn0.875X0.125N (X = Mn, Ge, and Sn). Based on the optimal exchange-correlation functional, our results demonstrate that X (X = Mn, Ge, and Sn) doping at Zn site could stabilize the noncollinear Γ5g AFM structure and produce magnetovolume effect (MVE). The predictions of Γ5g AFM ground state and MVE is further verified by the NPD results of Mn3Zn0.83Mn0.15N0.99. Intriguingly, this special magnetic structure with strong spin–lattice coupling can be tunable to achieve ZTE behavior. On the basis of these results we suggest that frustrated magnetic systems with noncollinear Γ5g AFM structure of Mn atoms i...
- Published
- 2015
39. First-Principles Study of Sc1−x Tix F3 (x ≤ 0.375): Negative Thermal Expansion, Phase Transition, and Compressibility
- Author
-
Kewen Shi, Sihao Deng, Lei Wang, Cong Wang, Huiqing Lu, Ying Sun, Xiaoyun Zhang, and Pengwei Hu
- Subjects
Phase transition ,Atomic orbital ,Negative thermal expansion ,Chemistry ,Thermal ,Degenerate energy levels ,Materials Chemistry ,Ceramics and Composites ,Compressibility ,Thermodynamics ,Thermal expansion ,Stiffening - Abstract
We present the first-principles investigation of Sc1−xTixF3 (x ≤ 0.375). Controllable thermal expansion of Sc1−xTixF3 is achieved by different Ti contents. The negative thermal expansion (NTE) behavior is weakened gradually with increasing Ti content, which is consistent with experimental measurements. The Jahn–Teller effect plays an important role in the cubic-to-rhombohedral phase transition, which stems from the enhanced energy stability when the 3d orbitals of Ti3+ cation split into triply degenerate t2g and eg sets. The unusual thermal stiffening of Sc1−xTixF3 is found, which is similar to that of Sc1−xYxF3 and Sc1−xAlxF3 but contrary to other NTE materials.
- Published
- 2015
40. Metal fluorides, a new family of negative thermal expansion materials
- Author
-
Huiqing Lu, Kewen Shi, Cong Wang, Sihao Deng, Pengwei Hu, Lei Wang, Ying Sun, and Xiaoyun Zhang
- Subjects
Metal ,Materials science ,Negative thermal expansion ,visual_art ,Metals and Alloys ,visual_art.visual_art_medium ,Mineralogy ,Metal fluorides ,Engineering physics ,Thermal expansion ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
In the past decades, the families of negative thermal expansion (NTE) materials have been in the uninterrupted growth with more new NTE materials reported; in particular, metal fluorides as the new members begin to draw attention. Herein, recent progress on the NTE properties of metal fluorides is reviewed, including compounds, mechanisms and the control of thermal expansion. Although some achievements have been made, there are still great development prospects. More in-depth investigations on metal fluorides with NTE behavior are expected.
- Published
- 2015
41. Invar-like Behavior of Antiperovskite Mn3+xNi1–xN Compounds
- Author
-
Hui Wu, Laifeng Li, Kewen Shi, Lei Wang, Sihao Deng, Rongjin Huang, Cong Wang, Huiqing Lu, Ying Sun, Muhammad Imran Malik, Qingzhen Huang, and Jun Yan
- Subjects
Materials science ,Magnetic structure ,Condensed matter physics ,General Chemical Engineering ,Doping ,Neutron diffraction ,General Chemistry ,engineering.material ,Thermal expansion ,Antiperovskite ,Ferromagnetism ,Materials Chemistry ,engineering ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Invar - Abstract
The antiperovskite Mn3+xNi1–xN compounds have been synthesized and characterized by a variety of experimental techniques. After Mn doping at the Ni site, both ferromagnetic characteristics and an Invar-like effect were observed in the antiferromagnetic host material. The observed Invar-like behavior was assumed to be related to the characteristic magnetic structure induced by the doping. Neutron diffraction results prove that the Mn doping stabilizes the special Γ5g antiferromagnetic phase with strong spin–lattice coupling that can be tuned to achieve Invar-like behavior. The magnetovolume effect (MVE) and significant correlation between spin and lattice were confirmed for the Γ5g magnetic phase by the first-principles calculations. Moreover, Mn 3d electrons were revealed to be the key factor for the MVE from the calculations. Our study presents a new mechanism for precisely controlling the zero thermal expansion of a single compound by achieving the special Γ5g magnetic phase of Mn atoms.
- Published
- 2015
42. Rectifying Characteristics and Semiconductor-Metal Transition Induced by Interfacial Potential in the Mn
- Author
-
Kewen, Shi, Cong, Wang, Ying, Sun, Lei, Wang, Sihao, Deng, Pengwei, Hu, Huiqing, Lu, Weichang, Hao, Tianmin, Wang, and Weihua, Tang
- Abstract
The Mn
- Published
- 2017
43. Study of structure of Mn3Cu0.5Ge0.5N/Cu composite with nearly zero thermal expansion behavior around room temperature
- Author
-
Lihua Chu, Jun Yan, Sihao Deng, Kewen Shi, Huiqing Lu, Cong Wang, Ying Sun, and Zaixing Shi
- Subjects
Materials science ,Mechanics of Materials ,Mechanical Engineering ,Composite number ,Metallurgy ,Metals and Alloys ,Zero (complex analysis) ,General Materials Science ,Structured model ,Composite material ,Condensed Matter Physics ,Chemical reaction ,Thermal expansion - Abstract
An Mn3Cu0.5Ge0.5N/Cu composite was synthesized with 50 wt.% Cu and 50 wt.% Mn3Cu0.5Ge0.5N. The composite has a nearly zero thermal expansion behavior around room temperature and consists of Cu, Mn3Cu0.5Ge0.5N with a small number of MnO particles. There are no chemical reactions between these phases and the thermal expansion property of the composite is stable. Based on the distribution of Cu and Mn3Cu0.5Ge0.5N phases in the composite, we built a structure model to clarify the stability of Mn3Cu0.5Ge0.5N/Cu composite.
- Published
- 2014
44. Phase transitions and magnetocaloric effect in Mn3Cu0.89N0.96
- Author
-
Kewen Shi, Huiqing Lu, Lihua Chu, Hui Wu, Sihao Deng, Qingzhen Huang, Cong Wang, Jun Yan, Ying Sun, and Zaixing Shi
- Subjects
Quantum phase transition ,Phase transition ,Materials science ,Polymers and Plastics ,Condensed matter physics ,Metals and Alloys ,Electronic, Optical and Magnetic Materials ,Paramagnetism ,Antiperovskite ,Tetragonal crystal system ,Ferromagnetism ,Ceramics and Composites ,Magnetic refrigeration ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons - Abstract
We report a large magnetic entropy change observed in the antiperovskite Mn 3 Cu 0.89 N 0.96 . Based on the heat flow peak measured by differential scanning calorimetry, the total entropy change according to the structural transition (tetragonal to cubic) was calculated to be ∼60 J kg –1 K –1 while the magnetic entropy change accounts for ∼22.5% of the total entropy under a 50 kOe magnetic field at 145 K. To clarify the origin of the magnetic entropy change, we managed to control the structure transition using a magnetic field. It was found that the magnetic entropy change originates from the transformation from antiferromagnetic (AFM) to ferromagnetic (FM) as well as from the phase transition from cubic to tetragonal under the magnetic field. In the tetragonal phase, a magnetic field can drive the AFM component to transform gradually to the FM component. The magnetic field can also change the phase fraction in the tetragonal and cubic two-phase coexistence region, a similar behavior to that induced by temperature. In the current system, only 5.4% of the cubic phase transforms to the tetragonal phase at 5 Tesla (T), indicating there is still much latent entropy in Mn 3 Cu 0.89 N 0.96 .
- Published
- 2014
45. Fully-dense Mn3Zn0.7Ge0.3N /Al composites with zero thermal expansion behavior around room temperature
- Author
-
Sihao Deng, Kewen Shi, Xin Tan, Cong Wang, Gaohui Wu, Chang Zhou, and Qiang Zhang
- Subjects
010302 applied physics ,Materials science ,Composite number ,Electronic packaging ,Modulus ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Infiltration (HVAC) ,01 natural sciences ,Thermal expansion ,0103 physical sciences ,General Materials Science ,Composite material ,0210 nano-technology - Abstract
Mn3Zn0.7Ge0.3N/Al composites were successfully fabricated by pressure infiltration technology. The large positive thermal expansion of Al is suppressed by adding Mn3Zn0.7Ge0.3N component. Nearly zero thermal expansion is achieved in the composite with 30 vol.% Mn3Zn0.7Ge0.3N. Moreover, the bending stress and modulus of Mn3Zn0.7Ge0.3N/Al composites increase gradually with increasing Mn3Zn0.7Ge0.3N content. The low thermal expansion and good mechanical properties of these materials could be beneficial to the electronic packaging and precision fields.
- Published
- 2019
46. Large spin Hall effect of perpendicularly magnetized β-W/CoFeB/MgO layers with high thermal stability
- Author
-
Chao Zhao, Jianfeng Gao, Shouzhong Peng, Weisheng Zhao, Huaiwen Yang, Kaihua Cao, Lezhi Wang, and Kewen Shi
- Subjects
010302 applied physics ,Diffraction ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Annealing (metallurgy) ,General Engineering ,General Physics and Astronomy ,01 natural sciences ,Condensed Matter::Materials Science ,Magnetization ,CMOS ,0103 physical sciences ,Perpendicular ,Spin Hall effect ,Astrophysics::Solar and Stellar Astrophysics ,Torque ,Thermal stability - Abstract
We report a robust perpendicularly magnetized β-W/CoFeB/MgO multilayer structure. For the first time, we demonstrate efficient spin–orbit torque (SOT) switching and a highly thermally stable annealing process with this structure using X-ray diffraction tests, the harmonic technique, and SOT-driven magnetization switching measurements. These results may enable applications of SOT-based magnetic random access memory, which is required for integration in the CMOS back-end-of-line process.
- Published
- 2019
47. Baromagnetic Effect in Antiperovskite Mn3 Ga0.95 N0.94 by Neutron Powder Diffraction Analysis
- Author
-
Hui Wu, Kewen Shi, Jun Yan, Lei Wang, Sihao Deng, Ying Sun, Qingzhen Huang, Huiqing Lu, Muhammad Imran Malik, Pengwei Hu, and Cong Wang
- Subjects
Neutron powder diffraction ,Materials science ,Condensed matter physics ,Magnetic structure ,Mechanical Engineering ,Neutron diffraction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Pressure field ,Antiperovskite ,Tetragonal crystal system ,Crystallography ,Mechanics of Materials ,0103 physical sciences ,General Materials Science ,010306 general physics ,0210 nano-technology ,Powder diffraction ,Spin-½ - Abstract
A baromagnetic effect in a novel tetragonal magnetic structure is introduced by vacancies in Mn3 Ga0.95 N0.94 , due to the change of the Mn-Mn distance and their spin re-orientation induced by a pressure field. This effect is proven for the first time in antiperovskite compounds by neutron powder diffraction analysis. This feature will enable wide applications in magnetoelectric devices and intelligent instruments.
- Published
- 2016
48. Near-zero temperature coefficient of resistivity associated with magnetic ordering in antiperovskite Mn3+xNi1−xN
- Author
-
Lei Wang, Qingzhen Huang, Kewen Shi, Hui Wu, Pengwei Hu, Sihao Deng, Cong Wang, and Ying Sun
- Subjects
010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Scattering ,Neutron diffraction ,Doping ,02 engineering and technology ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic susceptibility ,Antiperovskite ,Electrical resistivity and conductivity ,0103 physical sciences ,0210 nano-technology ,human activities ,Temperature coefficient - Abstract
The near-zero temperature coefficient of resistivity (NZ-TCR) behavior is reported in the antiperovskite compounds Mn3+xNi1−xN (0 ≤ x ≤ 0.333). Our results indicate that the broad temperature range (above 275 K extending to above 220 K) of NZ-TCR is obtained by Mn doping at the Ni site. The short-range magnetic ordering is revealed by both neutron powder diffraction and inverse magnetic susceptibility. Further, we find a strong correlation between the anomalous resistivity change of Mn3+xNi1−xN from the metal-like to the NZ-TCR behavior and the lack of the long-range magnetic ordering. The possible mechanism of NZ-TCR behavior is discussed using the spin-disorder scattering model.
- Published
- 2016
49. Nitrogen-Induced Change of Magnetic Properties in Antiperovskite-Type Carbide: Mn 3 InC
- Author
-
Pengwei Hu, Muhammad Imran Malik, Sihao Deng, Cong Wang, Kewen Shi, and Ying Sun
- Subjects
Magnetization ,Antiperovskite ,Paramagnetism ,Materials science ,Ferromagnetism ,Condensed matter physics ,Ferrimagnetism ,Metastability ,General Physics and Astronomy ,Antiferromagnetism ,Curie temperature ,Condensed Matter::Strongly Correlated Electrons - Abstract
The effects of N substitution on the magnetic properties of Mn3InC1−xNx (0.0 ≤ x ≤ 0.7) are investigated systematically. Partial substitution of N for C leads to the monotonic reduction in both the Curie temperature TC and saturated magnetization MS. The final results obtained from thermo-magnetic curves demonstrate that Mn3InC1−xNx samples show a magnetic phase transition from a paramagnetic (PM) state to a ferrimagnetic (FIM) state consisting of ferromagnetic (FM) and antiferromagnetic (AFM) components. In addition, there is a competition between the AFM component and the FM component in the FIM state with the change of the N-doped content. Magnetic measurements of Mn3InC at 100 Oe and 5000 Oe indicate the metastability and the coexistence of different magnetic phases at lower temperature. The spans of FIM phase broaden gradually with further N doping. The mechanism for the induction of the complicated magnetic state is still in controversy. However, the results clearly show that the doping at the X site in antiperovskite Mn3AX materials is as useful as that of the A and Mn sites.
- Published
- 2015
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