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The analysis on IP signals in TEM response based on SVD 被引量:4
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作者 余传涛 刘鸿福 +2 位作者 张新军 杨德义 李自红 《Applied Geophysics》 SCIE CSCD 2013年第1期79-87,119,共10页
During transient electromagnetic method (TEM) exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon (a voltage change from positive to negative) caused by the influence of the i... During transient electromagnetic method (TEM) exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon (a voltage change from positive to negative) caused by the influence of the induced polarization (IP) effect, which affects the depth and precision of the TEM detection. The conventional inversion method is inefficient because it is difficult to process the data. In this paper, the Cole-Cole model is adopted to analyze the effect of Dc resistivity, chargeability, time constant, and frequency exponent on the TEM response in an homogeneous half space model. Singular Value Decomposition (SVD) is used to invert the measured TEM data, and the Dc resistivity, chargeability, time constant and frequency exponent were extracted from the measured TEM data in the mine area. The extracted parameters are used for interpreting the detection result as a supplement. This reveals why the TEM data acquired in the area has a low resolution. It was found that the DC resistivity and time constant do not significantly change the results, however, the chargeability and frequency exponent have a significant effect. Because of these influences, the SVD method is more accurate than the conventional method in the apparent resistivity profile. The area of the copper mine is confined accurately based on the SVD inverted data. The conclusion has been verified by drill and is identical to the practical geological situation. 展开更多
关键词 SVD method TEM response IP effects Cole-Cole models
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Improvement on Electrical Properties and Magnetoresistance Induced by Pd or Ag Addition in Lao.67(Ca0.65Ba0.35)0.33MnO3 Manganites
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作者 原晓波 任俊峰 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第4期431-438,J0002,共9页
Electrical properties and magnetoresistance have been studied in two series of xAg-La0.67(Ca0.65Ba0.35)0.33MnO3 and xPd-La0.67(Ca0.65Ba0.35)0.33MnO3 (abbreviated by xAg-LCBMO and xPd-LCBMO) composites. Both Pd a... Electrical properties and magnetoresistance have been studied in two series of xAg-La0.67(Ca0.65Ba0.35)0.33MnO3 and xPd-La0.67(Ca0.65Ba0.35)0.33MnO3 (abbreviated by xAg-LCBMO and xPd-LCBMO) composites. Both Pd and Ag addition induce a decrease in resistivity and an increase in temperature at which the resistivity reaches its maximum. This is mainly due to the improvement of grain boundaries caused by the segregation of good conductive metal grains on the grain boundaries/surfaces. In addition, both Pd and Ag addition induce a large enhancement of room temperature magnetoresistance (RTMR). Note that 27% molar ratio of Ag addition induces a large RTMR of about 70%, about ten times larger than pure LCBMO, whereas 27% molar ratio Pd addition brings a much larger RTMR of about 170%. The large enhancements of MR can be attributed to the decrease in resistivity of the samples caused by the good conductive metal. On the other hand, the polarization of Pd atoms near the Mn ions on the grain surfaces/boundaries plays a very im-portant role in the increase in MR, which induces a large number of spin clusters in Pd-added samples. 展开更多
关键词 Colossal magnetoresistance Ag-added manganite Pd-added manganite Roomtemperature magnetoresistance Spin cluster Polarization of Pd atom
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金属/介质/金属光栅结构强化吸收特性
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作者 张玉涛 宣益民 《工程热物理学报》 EI CAS CSCD 北大核心 2014年第2期358-361,共4页
本文从电磁场理论出发,研究了单层光栅的金属/介质/金属结构的共振,利用严格耦合波方法计算了金属/介质/金属光栅结构表面的光谱特性,利用金属/介质/金属膜层结构的色散关系和等效LC回路模型两种理论对金属/介质/金属光栅结构表面的共... 本文从电磁场理论出发,研究了单层光栅的金属/介质/金属结构的共振,利用严格耦合波方法计算了金属/介质/金属光栅结构表面的光谱特性,利用金属/介质/金属膜层结构的色散关系和等效LC回路模型两种理论对金属/介质/金属光栅结构表面的共振现象进行研究,讨论了几何参数对金属/介质/金属光栅结构共振的影响,结果表明单层光栅的金属/介质/金属结构的共振由金属/介质界面上的表面等离子极化之间的耦合产生。 展开更多
关键词 磁极化效应 表面等离子极 等效LC回路
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Ferroelectric control of single-molecule magnetism in 2D limit 被引量:2
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作者 Xinwei Wang Chengcheng Xiao +8 位作者 Chao Yang Miaogen Chen Shengyuan A.Yang Jun Hu Zhaohui Ren Hui Pan Wenguang Zhu Zhu-An Xu Yunhao Lu 《Science Bulletin》 SCIE EI CAS CSCD 2020年第15期1252-1259,M0003,共9页
The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices.Here,based on first-principles calculations,a strong magnetoelectric effect is ... The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices.Here,based on first-principles calculations,a strong magnetoelectric effect is proposed to effectively switch on/off the magnetic states as well as alter the in-plane/perpendicular easy axes of metal-phthalocyanine molecules(MPc)by reversing the electric polarization of the underlying two-dimensional(2D)ferroelectric a-In2Se3 substrate with the application of an external electric field.The mechanism originates from the different hybridization between the molecule and the ferroelectric substrate in which the different electronic states of surface Se layer play a dominant role.Moreover,the magnetic moments and magnetic anisotropy energies(MAE)of OsPc/In2Se3 can be further largely enhanced by a functionalized atom atop the OsPc molecule.The I-OsPc/In2Se3 system possesses large MAE up to 30 meV at both polarization directions,which is sufficient for room-temperature applications.These findings provide a feasible scheme to realize ferroelectric control of magnetic states in 2D limit,which have great potential for applications in nanoscale electronics and spintronics. 展开更多
关键词 Magnetoelectric effect Two-dimensional ferroelectric Single-molecular magnets In2Se3 Metal-phthalocyanine molecules
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