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1. The on-orbit calibration of DArk Matter Particle Explorer

Author

Ambrosi, G., An, Q., Asfandiyarov, R., Azzarello, P., Bernardini, P., Cai, M. S., Caragiulo, M., Chang, J., Chen, D. Y., Chen, H. F., Chen, J. L., Chen, W., Cui, M. Y., Cui, T. S., Dai, H. T., D'Amone, A., De Benedittis, A., De Mitri, I., Ding, M., Di Santo, M., Dong, J. N., Dong, T. K., Dong, Y. F., Dong, Z. X., Droz, D., Duan, K. K., Duan, J. L., D'Urso, D., Fan, R. R., Fan, Y. Z., Fang, F., Feng, C. Q., Feng, L., Fusco, P., Gallo, V., Gan, F. J., Gao, M., Gao, S. S., Gargano, F., Garrappa, S., Gong, K., Gong, Y. Z., Guo, J. H., Hu, Y. M., Huang, G. S., Huang, Y. Y., Ionica, M., Jiang, D., Jiang, W., Jin, X., Kong, J., Lei, S. J., Li, S., Li, X., Li, W. L., Li, Y., Liang, Y. F., Liang, Y. M., Liao, N. H., Liu, C. M., Liu, H., Liu, J., Liu, S. B., Liu, W. Q., Liu, Y., Loparco, F., Ma, M., Ma, P. X., Ma, S. Y., Ma, T., Ma, X. Q., Ma, X. Y., Marsella, G., Mazziotta, M. N., Mo, D., Niu, X. Y., Pan, X., Peng, X. Y., Peng, W. X., Qiao, R., Rao, J. N., Salinas, M. M., Shang, G. Z., Shen, W. H., Shen, Z. Q., Shen, Z. T., Song, J. X., Su, H., Su, M., Sun, Z. Y., Surdo, A., Teng, X. J., Tian, X. B., Tykhonov, A., Vitillo, S., Wang, C., Wang, H., Wang, H. Y., Wang, J. Z., Wang, L. G., Wang, Q., Wang, S., Wang, X. H., Wang, X. L., Wang, Y. F., Wang, Y. P., Wang, Y. Z., Wang, Z. M., Wen, S. C., Wei, D. M., Wei, J. J., Wei, Y. F., Wu, D., Wu, J., Wu, L. B., Wu, S. S., Wu, X., Xi, K., Xia, Z. Q., Xin, Y. L., Xu, H. T., Xu, Z. H., Xu, Z. L., Xu, Z. Z., Xue, G. F., Yang, H. B., Yang, P., Yang, Y. Q., Yang, Z. L., Yao, H. J., Yu, Y. H., Yuan, Q., Yue, C., Zang, J. J., Zhang, D. L., Zhang, F., Zhang, J. B., Zhang, J. Y., Zhang, J. Z., Zhang, L., Zhang, P. F., Zhang, S. X., Zhang, W. Z., Zhang, Y., Zhang, Y. J., Zhang, Y. Q., Zhang, Y. L., Zhang, Y. P., Zhang, Z., Zhang, Z. Y., Zhao, H., Zhao, H. Y., Zhao, X. F., Zhou, C. Y., Zhou, Y., Zhu, X., Zhu, Y., and Zimmer, S.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract

The DArk Matter Particle Explorer (DAMPE), a satellite-based cosmic ray and gamma-ray detector, was launched on December 17, 2015, and began its on-orbit operation on December 24, 2015. In this work we document the on-orbit calibration procedures used by DAMPE and report the calibration results of the Plastic Scintillator strip Detector (PSD), the Silicon-Tungsten tracKer-converter (STK), the BGO imaging calorimeter (BGO), and the Neutron Detector (NUD). The results are obtained using Galactic cosmic rays, bright known GeV gamma-ray sources, and charge injection into the front-end electronics of each sub-detector. The determination of the boundary of the South Atlantic Anomaly (SAA), the measurement of the live time, and the alignments of the detectors are also introduced. The calibration results demonstrate the stability of the detectors in almost two years of the on-orbit operation.

Published
2019
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2. Current-induced four-state magnetization switching by spin-orbit torques in perpendicular ferromagnetic trilayers

Author

Sheng, Y., Li, Y. C., Ma, X. Q., and Wang, K. Y.

Subjects
Physics - Applied Physics
Abstract

We demonstrated current-induced four-state magnetization switching in a trilayer system using spin-orbit torques. The memory device contains two Co layers with different perpendicular magnetic anisotropy, separated by a space layer of Pt. Making use of the opposite spin current at the top and bottom surface of the middle Pt layer, magnetization of both Co layers can be switched oppositely by the spin-orbit torques with different critical switching currents. By changing the current pulse forms through the device, the four magnetic states memory was demonstrated. Our device provides a new idea for the design of low power and high density spin-orbit torque devices.

Published
2018

3. Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons

Author

Ambrosi, G., An, Q., Asfandiyarov, R., Azzarello, P., Bernardini, P., Bertucci, B., Cai, M. S., Chang, J., Chen, D. Y., Chen, H. F., Chen, J. L., Chen, W., Cui, M. Y., Cui, T. S., D'Amone, A., De Benedittis, A., De Mitri, I., Di Santo, M., Dong, J. N., Dong, T. K., Dong, Y. F., Dong, Z. X., Donvito, G., Droz, D., Duan, K. K., Duan, J. L., Duranti, M., D'Urso, D., Fan, R. R., Fan, Y. Z., Fang, F., Feng, C. Q., Feng, L., Fusco, P., Gallo, V., Gan, F. J., Gao, M., Gao, S. S., Gargano, F., Garrappa, S., Gong, K., Gong, Y. Z., Guo, D. Y., Guo, J. H., Hu, Y. M., Huang, G. S., Huang, Y. Y., Ionica, M., Jiang, D., Jiang, W., Jin, X., Kong, J., Lei, S. J., Li, S., Li, X., Li, W. L., Li, Y., Liang, Y. F., Liang, Y. M., Liao, N. H., Liu, H., Liu, J., Liu, S. B., Liu, W. Q., Liu, Y., Loparco, F., Ma, M., Ma, P. X., Ma, S. Y., Ma, T., Ma, X. Q., Ma, X. Y., Marsella, G., Mazziotta, M. N., Mo, D., Niu, X. Y., Peng, X. Y., Peng, W. X., Qiao, R., Rao, J. N., Salinas, M. M., Shang, G. Z., Shen, W. H., Shen, Z. Q., Shen, Z. T., Song, J. X., Su, H., Su, M., Sun, Z. Y., Surdo, A., Teng, X. J., Tian, X. B., Tykhonov, A., Vagelli, V., Vitillo, S., Wang, C., Wang, H., Wang, H. Y., Wang, J. Z., Wang, L. G., Wang, Q., Wang, S., Wang, X. H., Wang, X. L., Wang, Y. F., Wang, Y. P., Wang, Y. Z., Wen, S. C., Wang, Z. M., Wei, D. M., Wei, J. J., Wei, Y. F., Wu, D., Wu, J., Wu, L. B., Wu, S. S., Wu, X., Xi, K., Xia, Z. Q., Xin, Y. L., Xu, H. T., Xu, Z. L., Xu, Z. Z., Xue, G. F., Yang, H. B., Yang, P., Yang, Y. Q., Yang, Z. L., Yao, H. J., Yu, Y. H., Yuan, Q., Yue, C., Zang, J. J., Zhang, C., Zhang, D. L., Zhang, F., Zhang, J. B., Zhang, J. Y., Zhang, J. Z., Zhang, L., Zhang, P. F., Zhang, S. X., Zhang, W. Z., Zhang, Y., Zhang, Y. J., Zhang, Y. Q., Zhang, Y. L., Zhang, Y. P., Zhang, Z., Zhang, Z. Y., Zhao, H., Zhao, H. Y., Zhao, X. F., Zhou, C. Y., Zhou, Y., Zhu, X., Zhu, Y., and Zimmer, S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

High energy cosmic ray electrons plus positrons (CREs), which lose energy quickly during their propagation, provide an ideal probe of Galactic high-energy processes and may enable the observation of phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been directly measured up to $\sim 2$ TeV in previous balloon- or space-borne experiments, and indirectly up to $\sim 5$ TeV by ground-based Cherenkov $\gamma$-ray telescope arrays. Evidence for a spectral break in the TeV energy range has been provided by indirect measurements of H.E.S.S., although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range $25~{\rm GeV}-4.6~{\rm TeV}$ by the DArk Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The majority of the spectrum can be properly fitted by a smoothly broken power-law model rather than a single power-law model. The direct detection of a spectral break at $E \sim0.9$ TeV confirms the evidence found by H.E.S.S., clarifies the behavior of the CRE spectrum at energies above 1 TeV and sheds light on the physical origin of the sub-TeV CREs., Comment: 18 pages, 6 figures, Nature in press, doi:10.1038/nature24475

Published
2017
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4. The DArk Matter Particle Explorer mission

Author

Chang, J., Ambrosi, G., An, Q., Asfandiyarov, R., Azzarello, P., Bernardini, P., Bertucci, B., Cai, M. S., Caragiulo, M., Chen, D. Y., Chen, H. F., Chen, J. L., Chen, W., Cui, M. Y., Cui, T. S., D'Amone, A., De Benedittis, A., De Mitri, I., Di Santo, M., Dong, J. N., Dong, T. K., Dong, Y. F., Dong, Z. X., Donvito, G., Droz, D., Duan, K. K., Duan, J. L., Duranti, M., D'Urso, D., Fan, R. R., Fan, Y. Z., Fang, F., Feng, C. Q., Feng, L., Fusco, P., Gallo, V., Gan, F. J., Gan, W. Q., Gao, M., Gao, S. S., Gargano, F., Gong, K., Gong, Y. Z., Guo, J. H., Hu, Y. M., Huang, G. S., Huang, Y. Y., Ionica, M., Jiang, D., Jiang, W., Jin, X., Kong, J., Lei, S. J., Li, S., Li, X., Li, W. L., Li, Y., Liang, Y. F., Liang, Y. M., Liao, N. H., Liu, Q. Z., Liu, H., Liu, J., Liu, S. B., Liu, W. Q., Liu, Y., Loparco, F., Lü, J., Ma, M., Ma, P. X., Ma, S. Y., Ma, T., Ma, X. Q., Ma, X. Y., Marsella, G., Mazziotta, M. N., Mo, D., Miao, T. T., Niu, X. Y., Pohl, M., Peng, X. Y., Peng, W. X., Qiao, R., Rao, J. N., Salinas, M. M., Shang, G. Z., Shen, W. H., Shen, Z. Q., Shen, Z. T., Song, J. X., Su, H., Su, M., Sun, Z. Y., Surdo, A., Teng, X. J., Tian, X. B., Tykhonov, A., Vagelli, V., Vitillo, S., Wang, C., Wang, Chi, Wang, H., Wang, H. Y., Wang, J. Z., Wang, L. G., Wang, Q., Wang, S., Wang, X. H., Wang, X. L., Wang, Y. F., Wang, Y. P., Wang, Y. Z., Wen, S. C., Wang, Z. M., Wei, D. M., Wei, J. J., Wei, Y. F., Wu, D., Wu, J., Wu, S. S., Wu, X., Xi, K., Xia, Z. Q., Xin, Y. L., Xu, H. T., Xu, Z. L., Xu, Z. Z., Xue, G. F., Yang, H. B., Yang, J., Yang, P., Yang, Y. Q., Yang, Z. L., Yao, H. J., Yu, Y. H., Yuan, Q., Yue, C., Zang, J. J., Zhang, C., Zhang, D. L., Zhang, F., Zhang, J. B., Zhang, J. Y., Zhang, J. Z., Zhang, L., Zhang, P. F., Zhang, S. X., Zhang, W. Z., Zhang, Y., Zhang, Y. J., Zhang, Y. Q., Zhang, Y. L., Zhang, Y. P., Zhang, Z., Zhang, Z. Y., Zhao, H., Zhao, H. Y., Zhao, X. F., Zhou, C. Y., Zhou, Y., Zhu, X., Zhu, Y., and Zimmer, S.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

The DArk Matter Particle Explorer (DAMPE), one of the four scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Sciences, is a general purpose high energy cosmic-ray and gamma-ray observatory, which was successfully launched on December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE scientific objectives include the study of galactic cosmic rays up to $\sim 10$ TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the search for dark matter signatures in their spectra. In this paper we illustrate the layout of the DAMPE instrument, and discuss the results of beam tests and calibrations performed on ground. Finally we present the expected performance in space and give an overview of the mission key scientific goals., Comment: 45 pages, including 29 figures and 6 tables. Published in Astropart. Phys

Published
2017
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5. Longitudinal Spin Seebeck Effect in Silver Strip on CoFe Film

Author

Sheng, Y., Yang, M. Y., Cao, Y., Cai, K. M., Wei, G. N., Yu, G. H., Zhang, B., Ma, X. Q., and Wang, K. Y.

Subjects
Condensed Matter - Materials Science
Abstract

We report the experimental observation of the spin Seebeck effect (SSE) in Ag/CoFe noble metal/magnetic metal bilayers with a longitudinal structure. Thermal voltages jointly generated by the anomalous Nernst effect (ANE) and the SSE were detected across the Ag/CoFe/Cu strip with a perpendicular thermal gradient. To effectively separate the SSE and the ANE part of the thermal voltages, we compared the experimental results between the Ag/CoFe/Cu strip and Cu/CoFe/Cu strip, where two samples processed with the heating power instead of the temperature difference through the thin CoFe film. The respective contributions of the ANE and SSE to thermal voltage were determined, and they have the ratio of 4:1. The spin current injected through CoFe/Ag interface is calculated to be 1.76 mA/W.

Published
2015

7. Room-temperature delayed giant magnetodielectric effects observed in Bi4Fe2TiO12 film

Author

Qiao, L. J., Lu, J., Xu, F., Chu, W. Y., and Ma, X. Q.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

This letter reports our experimental results on magnetic-field-induced aftereffects in solution derived Bi4Fe2TiO12 film, in which e' decreases as much as 600 times after treated in a 5T magnetic field as that of the pristine one. The phenomena are explained by an unusual spin-orbital coupling in film, where strong magnetic field provides drive force for spin polarized electrons of electrode to enter film, so as to form a ferromagnetic orbital state, increase the relaxation time of defect dipoles and then produce giant magnetodielectric effects. This process is reversible just by applying a opposite 0.5T magnetic field. Our findings have potential applications on magnetic fabrication of nanopatterns somehow to evade nanohazard, as well as on integraged phononic or photonic crystals on chip., Comment: This explanation of the experimental data was not correct

Published
2006

8. Magnetodielectric effect of Bi6Fe2Ti3O18 film under an ultra-low magnetic field

Author

Lu, J., Qiao, L. J., Ma, X. Q., and Chu, W. Y.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Good quality and fine grain Bi6Fe2Ti3O18 magnetic ferroelectric films with single-phase layered perovskite structure have been successfully prepared via metal organic decomposition (MOD) method. Results of low-temperature magnetocapacitance measurements reveal that an ultra-low magnetic field of 10 Oe can produce a nontrivial magnetodielectric (MD) response in zero-field-cooling condition, and the relative variation of dielectric constants in magnetic field is positive, i.e., MD=0.05, when T<55K, but negative with a maximum of MD=-0.14 when 55K

Published
2006
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11. INFLUENCE OF DIFFERENTIAL NITROGEN FORMS ON SEEDLING MORPHOLOGY OF FOUR WIDELY GROWN SPECIES IN SOUTHERN CHINA.

Author

GILANI, M. M., TIGABU, M., FAROOQ, T. H., RASHID, M. H. U., YASIN, G., ZUBAIR, M., AZHAR, M. F., CAI, L. P., AKRAM, M. A., LIU, B., and MA, X. Q.

Subjects
DIFFERENTIAL forms, CHINA fir, GERMINATION, NITROGEN fertilizers, POTASSIUM nitrate
Abstract

The rise in environmental nitrogen (N) is a worldwide concern, particularly in southern China, which contains highly N-contaminated areas. The ecological outcome of the increase in N should be paid additional consideration. Thus, this study was conducted to assess the impact of N on seed germination and seedling emergence of four timber species in subtropical southern China. We conducted a growth chamber experiment with three nitrogen fertilizers i.e., Ammonium sulfate (NH4)2SO4, Ammonium Nitrate (NH4NO3), and Potassium Nitrate (KNO3) with three concentrations (0.1%, 0.5% & 1%) along with control treatment (CK). We hypothesized that the impact of N on seed germination and seedling emergence would differ among species and N levels. Results showed that higher N concentration affected Cunninghamia lanceolata, Fokienia hodginisi and Pinus massoniana seedlings compared with Phoebe zhennan. Overall, fresh and dry weight as well as the length of broad-leaved species was better than coniferous and pine species. It was observed that 1% KNO3 solution enhanced the germination capacity, germination time, radicle, and hypocotyl elongation along with fresh and dry weights as compared to (NH4)2SO4 and NH4NO3. The outcome showed that deposition of 1% KNO3 is promising to increase the germination of seed and seedlings emergence. [ABSTRACT FROM AUTHOR]

Published
2023
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17. Observation of weak antilocalization effect in high-quality ScNiBi single crystal.

Author

Deng, L., Liu, Z. H., Ma, X. Q., Hou, Z. P., Liu, E. K., Xi, X. K., Wang, W. H., Wu, G. H., and Zhang, X. X.

Subjects
SINGLE crystals, MAGNETORESISTANCE, NARROW gap semiconductors, SPIN-orbit coupling constants, BAND gaps
Abstract

In this paper, we have successfully grown the high-quality ScNiBi single crystals by a Bi flux method and investigated their electronic-transport properties. It was found that the ScNiBi single crystal is a gapless semiconductor with positive linear magnetoresistance (MR). Moreover, the field-dependent MR in the low-field region has demonstrated obvious weak antilocalization (WAL) effect below 50 K. The extremely large prefactor α and angle-dependent magnetoconductance ΔGxx suggest that the WAL effect originates from the contribution of a strong bulk spin-orbital coupling. [ABSTRACT FROM AUTHOR]

Published
2017
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26. COMPARISON OF CALCIUM ACCUMULATION, DISTRIBUTION, AND USE EFFICIENCY AMONG CHINESE FIR (CUNNINGHAMIA LANCEOLATA (Lamb.) Hook) CLONES.

Author

ZHENG, S. S., ZHANG, H., GUO, H. L., MA, X. Q., LIN, W. J., and WU, P. F.

Subjects
CHINA fir, PLANT clones, FIR, SOIL fertility, LAMBS, CALCIUM
Abstract

Screening Chinese fir (Cunninghamia lanceolata) clones with efficient calcium utilization is an effective strategy to maintain soil fertility and improve their productivity and adaptability to nutrient stress habitats. The calcium content of 17-year-old Chinese fir progenies was measured, and calcium accumulation, distribution, and utilization efficiency were compared to select clones that had high calcium utilization efficiency (CaUE). Significant differences in calcium content and accumulation were observed in different vegetative organs and clones. The highest average calcium content and accumulation were in needles, and the lowest averages were in stems and dead branches. Clone M43 had the highest total calcium accumulation, whereas clone M37 had the lowest. Among the tested clones, the CaUE of the whole tree for M23, M37, and M25 was significantly high, whereas that for M43 was the lowest. The CaUE of stems was the highest in M23 and lowest in M17. Thus, calcium content and accumulation in the vegetative organs are important factors affecting the CaUE of whole trees and stems of different Chinese fir clones. Considering the comprehensive CaUE and bioaccumulation in whole trees and stems, M23, M25, and M10 were clones with high CaUE that should be used in future studies on high-yield plantations. [ABSTRACT FROM AUTHOR]

Published
2022
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31. Static magnetic solution in magnetic composites with arbitrary susceptibility inhomogeneity and anisotropy.

Author

Wang, J. J., Song, Y., Ma, X. Q., Long-Qing Chen, and Ce-Wen Nan

Subjects
MAGNETIC alloys, FOURIER integrals, MAGNETIC reconnection, MATHEMATICAL models, ANISOTROPY, MAGNETIC susceptibility
Abstract

The static magnetic solutions in magnetic composites with arbitrary susceptibility inhomogeneity and anisotropy are accurately computed using an efficient numerical algorithm based on a proposed Fourier spectral iterative perturbation method for 3-dimensional systems. An advantage of this method is that the interphase boundary conditions are automatically considered without explicitly tracking interphase interfaces in the composites. This method can be conveniently implemented in phase-field modeling of microstructure evolution in systems with inhomogeneous susceptibility as well as inhomogeneous spontaneous magnetization distributions. Based on the proposed method, the effects of microstructures including the susceptibility mismatch between the inclusions and matrix, inclusions volume fraction, and inclusions arrangement on the effective susceptibility and local static magnetic field distribution of the composite are investigated. It is found that the interactions among the inclusions embedded in the matrix play critical roles in determining the composite properties. [ABSTRACT FROM AUTHOR]

Published
2015
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32. Modelling current-induced magnetization switching in Heusler alloy Co2FeAl-based spin-valve nanopillar.

Author

Huang, H. B., Ma, X. Q., Liu, Z. H., Zhao, C. P., and Chen, L. Q.

Subjects
*MAGNETIZATION, *FERROMAGNETISM, *MAGNETISM, *ANISOTROPY, *CRYSTALLOGRAPHY
Abstract

We investigated the current-induced magnetization switching in a Heusler alloy Co2FeAl-based spin-valve nanopillar by using micromagnetic simulations. We demonstrated that the elimination of the intermediate state is originally resulted from the decease of effective magnetic anisotropy constant. The magnetization switching can be achieved at a small current density of 1.0×104 A/cm2 by increasing the demagnetization factors of x and y axes. Based on our simulation, we found magnetic anisotropy and demagnetization energies have different contributions to the magnetization switching. © 2014 AIP Publishing LLC. [ABSTRACT FROM AUTHOR]

Published
2014
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34. Realization of tetragonal Heusler alloy Mn3-xCrxGa for spintronic applications

Author

Zhang, Qiangqiang, Liu, Z H, Tan, Jingang, Ma, X Q, Cheng, Zhenxiang, Zhang, Qiangqiang, Liu, Z H, Tan, Jingang, Ma, X Q, and Cheng, Zhenxiang

Abstract

Tetragonal Heusler alloys with high coercivity field (H C ), low saturation magnetic moment and high Curie temperature (T C ) have been considered as promising candidates for spin transfer torque (STT) applications. In this paper, tetragonal Heusler alloys Mn 3-x Cr x Ga have been designed and realized in experiments by adjusting the ratio of Mn/Cr and selecting suitable heat treatment conditions. It has been found that Mn 3-x Cr x Ga (x = 0, 0.2, 0.3, 0.4, 0.5, 0.6 and 1) alloys exhibited multiple phase structures. As x > 0.5, both as-spun and as-annealed ribbons show pure B2-type body-centered cubic (b.c.c.) structure. The D0 22 -type tetragonal Heusler structure starts to appear in the matrix of cubic B2 structure as x = 0.5 in as-annealed ribbon samples, and gradually develops to pure tetragonal structure as x = 0.3. There is a significant structure difference between as-annealed and as-spun ribbons as x ≤ 0.2. Cu 3 Au-type face-centered cubic (f.c.c.) structure is observed for as-spun ribbons, while the annealed ribbons show pure tetragonal structure. The pure tetragonal Heusler alloys have hard-ferrimagnetic properties with Hc higher than 258 kA/m, accompanied by a high T C , large magnetic remanence (B r ) and low magnetic moment at room temperature, which are important factors for spin-transfer torque applications. Our work reveals the tunability of the magnetic and structural properties of Heusler alloys by changing the ratio of doping elements, providing a guidance for further searching for tetragonal Heusler alloys.

Published
2019

36. Follow-up management strategy for patients undergoing peritoneal dialysis during novel coronavirus pneumonia epidemic.

Author

WANG, Y., WANG, Y.-C., SONG, S.-H., ZHANG, H.-X., WANG, L., MA, X.-Q., ZHAO, C.-P., XU, M., TIAN, N., and CHEN, M.-H.

Abstract

OBJECTIVE: The study aimed to explore the best follow-up management strategy for patients undergoing peritoneal dialysis (PD) during the novel coronavirus pneumonia (NCP) epidemic. PATIENTS AND METHODS: Patients undergoing PD who were followed up during the NCP epidemic by our hospital were enrolled in this study. Because of the need to control the epidemic, a follow-up system was established during the epidemic period, with WeChat, QQ, and the telephone as the main methods of communication. Outpatient and emergency follow-ups were carried out to ensure the safety of dialysis and the prevention and control of the epidemic. The follow-up strategy included response measures related to the epidemic situation, prevention of peritonitis related to PD, water and salt control, exercise guidance, and psychological care. According to the patient’s condition, the appointment system was implemented, with one consulting room and one process for each patient. The emergency patients were isolated in accordance with the epidemic situation. RESULTS: Since January 2020, among the 580 patients undergoing PD who were followed up in our department and their families, none had NCP infection. During the epidemic period, the standard hemoglobin level and the inpatient rate decreased. Complications related to PD, such as peritonitis, cardiovascular complications caused by volume overload, and pulmonary infection, did not significantly increase, and the withdrawal rate and mortality rate decreased compared with those in the same period last year. CONCLUSIONS: The patient follow-up strategy during the epidemic period had a significant positive effect on preventing and controlling the epidemic. Furthermore, during the epidemic period, encouraging patients and caregivers to pay attention to protection at home, avoid going out, strengthen self-management, and other measures were beneficial to the control of kidney disease itself, which is worth promoting. The close relationship between doctors and patients during the epidemic had a positive effect on the occurrence of complications related to patients undergoing PD. [ABSTRACT FROM AUTHOR]

Published
2020

40. Micromagnetic simulation of spin-transfer switching in a full-Heusler Co2FeAl0.5Si0.5 alloy spin-valve nanopillar.

Author

Huang, H. B., Ma, X. Q., Liu, Z. H., Meng, F. Y., Xiao, Z. H., Wu, P. P., Shi, S. Q., and Chen, L. Q.

Subjects
*HYSTERESIS loop, *DIELECTRICS, *ELECTROMAGNETIC induction, *ANISOTROPY, *COBALT
Abstract

We investigated the spin-transfer switching in a full-Heusler Co2FeAl0.5Si0.5 alloy spin-valve nanopillar through micromagnetic simulation. A two-step switching hysteresis loop due to the fourfold in-plane magnetocrystalline anisotropy of Co2FeAl0.5Si0.5 layers was obtained. The simulation explains the experimental result of the resistance versus current hysteresis loop and yields good agreement with the measured critical current. Furthermore, the magnetization trajectory and magnetization distribution were shown and analyzed to elucidate the different characters of two-step switching. [ABSTRACT FROM AUTHOR]

Published
2011
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41. Large magnetization change and magnetoresistance associated with martensitic transformation in Mn2Ni1.36Sn0.32Co0.32 alloy.

Author

Liu, Z. H., Wu, Z. G., Ma, X. Q., Wang, W. H., Liu, Y., and Wu, G. H.

Subjects
MAGNETIZATION, MAGNETORESISTANCE, MARTENSITE, AUSTENITE, CONDUCTION electrons
Abstract

In this paper we report on the realization of magnetic field-induced martensitic phase transformation in Mn-rich Heusler alloy Mn2Ni1.36Sn0.32Co0.32. The saturation magnetization of the austenite reached 111 emu/g at 70 kOe, which decreased rapidly to 8 emu/g upon transforming to martensite. This is attributed to the crystallographic distortion from cubic structure to tetragonal structure with c/a > 1, turning the Mn moments at B sites and D sites from parallel alignment to antiparallel alignment. A large magnetoresistance of 40% was observed through the field-induced transformation. The increase of conduction electrons accompanying this field-induced martensitic transformation is estimated to be 67%. These intriguing properties render the alloy a good candidate for applications in smart devices. [ABSTRACT FROM AUTHOR]

Published
2011
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42. Temperature-pressure phase diagram and ferroelectric properties of BaTiO3 single crystal based on a modified Landau potential.

Author

Wang, J. J., Wu, P. P., Ma, X. Q., and Chen, L. Q.

Subjects
PHASE diagrams, FERROELECTRIC crystals, FERROELECTRICITY, LANDAU levels, DIELECTRICS
Abstract

A modified eighth-order Landau potential was proposed for the BaTiO3 single crystal by taking account into the quantum mechanical effects at low temperature. While all existing thermodynamic potentials for BaTiO3 fail to accurately describe the pressure dependence of ferroelectric transition temperatures, the temperature and hydrostatic pressure phase diagram constructed using the modified potential shows excellent agreement with experimental measurements by Ishidate, Abe, Takahashi, and Mori [Phys. Rev. Lett. 78, 2397 (1997)]. On the basis of the new proposed Landau potential, we calculated the dielectric coefficients, spontaneous polarizations, temperature-electric field phase diagram, and piezoelectric coefficients, all in good agreement well with existing experimental data. [ABSTRACT FROM AUTHOR]

Published
2010
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43. Lattice, elastic, polarization, and electrostrictive properties of BaTiO3 from first-principles.

Author

Wang, J. J., Meng, F. Y., Ma, X. Q., Xu, M. X., and Chen, L. Q.

Subjects
FERROELECTRIC crystals, THIN films, ELECTROMECHANICAL devices, ELASTICITY, MAGNETIC domain, FERROMAGNETIC materials, MAGNETIC coupling
Abstract

Predicting the domain structures and properties in both bulk single crystal and thin film ferroelectrics using the phase-field approach requires the knowledge of fundamental mechanical, electrical, and electromechanical coupling properties of a single-domain state. In this work, the elastic properties and structural parameters of cubic single crystals as well as tetragonal, orthorhombic, and rhombohedral BaTiO3 single domain states are obtained using first-principles calculations under the local density approximation. The calculated lattice constants, bulk modulus, and elastic constants are in good agreement with experiments for both the cubic paraelectric phase and the low-temperature ferroelectric phases. Spontaneous polarizations for all three ferroelectric phases and the electrostrictive coefficients of cubic BaTiO3 are also computed using the Berry’s phase approach, and the results agree well with existing experimentally measured values. [ABSTRACT FROM AUTHOR]

Published
2010
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44. Phase-field simulations of stress-strain behavior in ferromagnetic shape memory alloy Ni2MnGa.

Author

Wu, P. P., Ma, X. Q., Zhang, J. X., and Chen, L. Q.

Subjects
*STRAINS & stresses (Mechanics), *FERROMAGNETISM, *SHAPE memory alloys, *FERROMAGNETIC materials, *MAGNETIC domain, *MICROSTRUCTURE, *MAGNETIC fields
Abstract

The evolution of strain, magnetic domain structure, and martensite microstructure during compressive stress loading and unloading of Ni2MnGa was studied using a phase-field model at several selected magnetic fields. We observed a typical quasiplastic behavior at zero field and a pseudoelastic behavior at 300 kA/m. At an intermediate field, 150 kA/m, the stress-strain relation is partially pseudoelastic. It was demonstrated that the magnetic domain structure has little influence on the recovered strain while the demagnetization factor impacts the strain reversal. [ABSTRACT FROM AUTHOR]

Published
2008
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45. Micromagnetic simulations of current-induced magnetization switching in Co/Cu/Co nanopillars.

Author

Xiao, Z. H., Ma, X. Q., Wu, P. P., Zhang, J. X., Chen, L. Q., and Shi, S. Q.

Subjects
*MAGNETIZATION, *OSCILLATIONS, *SEMICONDUCTORS -- Fluctuations, *PROPERTIES of matter, *NANOSTRUCTURES, *ANISOTROPY
Abstract

We studied the current-induced magnetic switching in Co/Cu/Co nanopillars with an in-plane magnetization traversed by a perpendicular-to-plane spin-polarized current. The Landau-Lifshitz-Gilbert equation incorporating the spin transfer torque (STT) effect was employed. Magnetization switching was found to take place when the current density exceeds a threshold. It is accompanied by drastic oscillations near the magnetic reversal point. The switching time depends on the applied current density. The magnetization can also be switched by a sufficiently long square pulsed current. The roles of anisotropy, exchange, and demagnetization energies in the magnetization switching process of nanopillars are discussed. It is shown that the switching is mainly determined by the competition between STT and the Gilbert damping torque. [ABSTRACT FROM AUTHOR]

Published
2007
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46. Power-aware management for non-stationary service requests

Author

Ma X.-Q., Song X.-J., Liu W.-Y., and Zheng X.-F.

Subjects
Power management, Mathematical optimization, Engineering, business.industry, Real-time computing, PID controller, Fuzzy logic, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Power (physics), Distance correlation, Hit rate, Human multitasking, Timeout, business
Abstract

For multitasking environment of an embedded system, an improved method called hybrid model for power management algorithm was proposed for modeling of system with general distribution. First, the dynamic power management strategy algorithm was introduced, and the reason why it needed to be improved was expounded. Then, the Rescaled Range Analysis (R/S) method was used to analyze the long distance correlation of non-stationary time service requests and the corresponding strategy was selected depending on the different results. These strategies are remaining battery power timeout strategy, fuzzy not quite PID strategy and semi-Markov random strategy. Finally, the method for determining the strategy parameters was given and the strategy proposed in this paper was analyzed experimentally. The experimental results show that this strategy makes up for the deficiency of conventional dynamic power management strategy and has more extensive adaptability.Under the condition of 10% performance loss, the average system power consumption is reduced by 37%, and the hit rate is more than 60%. The algorithm reduces power consumption more efficiently than other methods, and is applicable in embedded systems.

Published
2014
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47. Robust fully-compensated ferrimagnetism and semiconductivity in inverse Heusler compounds: Ti2VZ (Z = P, As, Sb, Bi)

Author

Zhang, Y J, Liu, Z H, Liu, Guodong, Ma, X Q, Cheng, Zhenxiang, Zhang, Y J, Liu, Z H, Liu, Guodong, Ma, X Q, and Cheng, Zhenxiang

Abstract

Compensated ferrimagnets, due to their zero net magnetization and potential for large spin-polarization, have been attracting more and more attention in the field of spintronics. We demonstrate potential candidate materials among the inverse Heusler compounds Ti 2 VZ (Z = P, As, Sb, Bi) by first principles calculations. It is found that these compounds with 18 valence electrons per unit cell have zero net magnetic moment with compensated sublattice m agnetization, as anticipated by a variant of Slater-Pauling rule of M t = N V − 18, where M t is the total spin magnetic moment per formula unit and N V is the number of valence electrons per formula unit, and show semiconducting behavior in both spin channels with a moderate exchange splitting, as with ordinary ferromagnetic semiconductors. Furthermore, the fully compensated ferrimagnetism and semiconductivity are rather robust over a wide range of lattice contraction and expansion. Due to the above distinct advantages, these compounds will be promising candidates for spintronic applications.

Published
2018

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