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Start Over Author "Zhang Z" Journal applied physics letters
913 results on '"Zhang Z"'

213. Magnetic anisotropy of single-crystalline Mn3Sn in triangular and helix-phase states.

Author

Duan, T. F., Ren, W. J., Liu, W. L., Li, S. J., Liu, W., and Zhang, Z. D.

Subjects
MAGNETIC anisotropy, PHASE transitions, TEMPERATURE effect, ANTIFERROMAGNETISM, MAGNETIC structure, SINGLE crystals, MANGANESE compounds
Abstract

The magnetic structure and phase transitions in single-crystalline Mn3Sn with the D019 structure have been investigated by torque measurements and magnetic measurements. The results show that a triangular antiferromagnet (AFM) and a weak ferromagnet coexist above 270 K. At these temperatures, the torque measurements indicate a six-fold symmetry and another two-fold symmetry of the magnetic anisotropy. The [1120] direction is the lowest-energy state in the triangular configuration. At low temperatures, two AFM helix-phase states are found in an applied magnetic field (H): In one of them, the [1120] direction is the easiest deviation direction from the AFM state. In the other, it is the [0001] direction. The variation of the two states with temperature (T) and magnetic field is presented in an H-T phase diagram. [ABSTRACT FROM AUTHOR]

Published
2015
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214. Abnormal magnetic ordering and ferromagnetism in perovskite ScMnO3 film.

Author

Wang, F., Zhang, Y. Q., Liu, W., Ning, X. K., Bai, Y., Dai, Z. M., Ma, S., Zhao, X. G., Li, S. K., and Zhang, Z. D.

Subjects
MAGNETIC properties of perovskite, FERROMAGNETISM, MULTIFERROIC materials, PULSED laser deposition, MAGNETIC transitions, MAGNETIZATION
Abstract

Bulk multiferroic ScMnO3 is the stable hexagonal phase, and it is very difficult to prepare its perovskite orthorhombic phase even under high pressure. We fabricated the orthorhombic ScMnO3 thin film by pulsed laser deposition through suitable substrate LaAlO3 and found that nano-scale twin-like domains are naturally formed in the thin film. Magnetic properties of the orthorhombic ScMnO3 thin films show that, besides normal antiferromagnetic ordering at 47 K, an anomalous magnetic transition occurs at 27K for 60 nm film and at 36K for 150 nm film only along the c-axis, which is absent in the ab-plane. Moreover, the second magnetic transition for both films is suppressed when the applied field increases from 1 kOe to 10 kOe. In addition, the ferromagnetism shows up in both films at 10 K, and saturation magnetization increases dramatically in 60 nm film compared with 150 nm film. We propose that the second magnetic transition might be more of lattice strain effect and also related to magnetism-induced ferroelectric polarization in orthorhombic RMnO3 thin films and low-temperature ferromagnetic properties in our films originate from the nano-scale twin-like domain structure. [ABSTRACT FROM AUTHOR]

Published
2015
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215. The tunable negative permittivity and negative permeability of percolative Fe/Al2O3 composites in radio frequency range.

Author

Sun, K., Fan, R. H., Zhang, Z. D., Yan, K. L., Zhang, X. H., Xie, P. T., Yu, M. X., and Pan, S. B.

Subjects
IRON composites, RADIO frequency, PERMITTIVITY, PERMEABILITY, RESONANCE frequency analysis, ELECTROMAGNETIC wave absorption
Abstract

The electromagnetic properties including ac conductivity, permittivity, and permeability of percolative Fe/Al2O3 composites, which were prepared by in-situ synthesis process, are investigated in the radio frequency range. There is an obvious percolation transition with the increase of iron contents. When iron content is beyond but near the percolation threshold, the negative permittivity and permeability are simultaneously obtained from 631MHz to 1GHz in sample FA30. Further increasing iron content, the Fano-like resonances are observed, and the resonance frequency where the permittivity changes from negative to positive shifts to lower frequency. In addition, the frequency region of negative permittivity and negative permeability are not overlapped any more. Hopefully, the percolative Fe/Al2O3 composites with tunable negative permittivity and negative permeability can be used as electromagnetic wave absorber. [ABSTRACT FROM AUTHOR]

Published
2015
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216. High magnetic-refrigeration performance of plate-shaped La0.5Pr0.5Fe11.4Si1.6 hydrides sintered in high-pressure H2 atmosphere.

Author

Sun, N. K., Guo, J., Zhao, X. G., Si, P. Z., Huang, J. H., and Zhang, Z. D.

Subjects
LANTHANUM compounds, MAGNETIC cooling, HYDRIDES, SINTERING, MAGNETIC entropy
Abstract

La(Fe, Si)13 hydride is regarded as one of the most promising room-temperature refrigerants. However, to use the alloys in an active magnetic regenerator machine, it is vital to prepare thin refrigerants. In this work, a high H2 gas pressure of 50 MPa was employed to suppress the desorption of hydrogen atoms during the sintering process of plate-shaped La0.5Pr0.5Fe11.4Si1.6 hydrides. At 330K, a high-density sintered thin plate shows a large magnetic-entropy change ΔSm of 15.5 J/kgK (106mJ/cm³K) for a field change of 2T. The volumetric DSm is almost twice as large as that of bonded La(Fe,Si)13 hydrides. Favorably, hysteresis is almost absent due to the existence of micropores with a porosity of 0.69% which has been analyzed with high-resolution X-ray microtomography. [ABSTRACT FROM AUTHOR]

Published
2015
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217. Defect states and charge trapping characteristics of HfO2 films for high performance nonvolatile memory applications.

Author

Zhang, Y., Shao, Y. Y., Lu, X. B., Zeng, M., Zhang, Z., Gao, X. S., Zhang, X. J., Liu, J.-M., and Dai, J. Y.

Subjects
HAFNIUM oxide, ION traps, NONVOLATILE memory, CRYSTAL structure, PHOTOLUMINESCENCE measurement
Abstract

In this work, we present significant charge trapping memory effects of the metal-hafnium oxide-SiO2-Si (MHOS) structure. The devices based on 800 °C annealed HfO2 film exhibit a large memory window of ~5.1 V under ±10 V sweeping voltages and excellent charge retention properties with only small charge loss of ~2.6% after more than 104 s retention. The outstanding memory characteristics are attributed to the high density of deep defect states in HfO2 films. We investigated the defect states in the HfO2 films by photoluminescence and photoluminescence excitation measurements and found that the defect states distributed in deep energy levels ranging from 1.1 eV to 2.9 eV below the conduction band. Our work provides further insights for the charge trapping mechanisms of the HfO2 based MHOS devices. [ABSTRACT FROM AUTHOR]

Published
2014
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220. Wavy cleavage fracture of bulk metallic glass

Author

Zhang, Z. F., primary, Wu, F. F., additional, Gao, W., additional, Tan, J., additional, Wang, Z. G., additional, Stoica, M., additional, Das, J., additional, Eckert, J., additional, Shen, B. L., additional, and Inoue, A., additional

Published
2006
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228. Formation of p-type MgZnO by nitrogen doping

Author

Wei, Z. P., primary, Yao, B., additional, Zhang, Z. Z., additional, Lu, Y. M., additional, Shen, D. Z., additional, Li, B. H., additional, Wang, X. H., additional, Zhang, J. Y., additional, Zhao, D. X., additional, Fan, X. W., additional, and Tang, Z. K., additional

Published
2006
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