Papers by Author: Zhi Gao Huang

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Authors: Heng Lai, Zhi Gao Huang, Rongquan Gai, Shui Yuan Chen, You Wei Du
Abstract: The thin polycrystalline Co films with different annealed time were prepared by magnetron sputtering method. XRD and hysteresis loops of the samples were measured. A mean field equation with Heisenberg model for calculating dynamic scaling was derived. The experimental and simulated results indicate that, the scaling law, A=A0+H0 a ω b, describes well dynamic magnetization along easy and hard axes for the anisotropy magnetic films; the anisotropy scaling exponents exist clearly in the anisotropy films; the simulated results are consistent with the experimental those.
Authors: Shang Dong Li, Zhi Gao Huang, Guo Xia Zhao, Wen Qin Zou, You Liao Zheng, You Wei Du
Abstract: The size effect of magnetocaloric effect (MCE) in CoCr2O4 has been investigated by comparing two samples with different crystal sizes. One is bulk CoCr2O4 sample (referred as A), and the other is a nanocrystalline CoCr2O4 sample (referred as B). It has been found that crystal size dramatically affects the magnetic properties and MCE for CoCr2O4, and that the nanocrystalline material is more favorable for application than the bulk material. The above results are explained in terms of the effect of small size and its distribution for sample B on the intrinsic magnetic properties and magnetic entropy change.
Authors: Lei Tang, Shui Yuan Chen, Hui Qin Zhang, Zhi Gao Huang
Abstract: In this paper, Pulsed laser deposition (PLD) is attempted to be an alternative synthesis method for Cu-Ga-In (CIGS) thin films. Cu-In-Ga prefabricated metal films were grown on the quartz substrates by PLD method. Then the CIGS films with different Se content were synthesized by the post-selenization(Se)-annealing processes. The structure, element component proportion and optical properties of the CIGS films were investigated. The experimental results indicate that the CIGS films can be well obtained by the PLD method with Se-annealing. The performances of the CIGS films are much affect by the Se-annealing processes, including Se-annealing temperature, annealing time, and the way of Se-annealing. The CIGS films prepared by PLD method with Se-annealing present fine visible light absorption properties.
Authors: Hong Zhang, Shui Yuan Chen, Su Zhen Tang, Wen Pao Ke, Heng Lai, Zhi Gao Huang
Abstract: La2/3(Ca0.6Ba0.4)1/3Mn1-xVxO3 (x=0, 0.03, 0.05, 0.07, 0.10, 0.15, 0.20) nanoparticles were synthesized using sol-gel technology. The experimental results reveal that, (1) the substitution of V for Mn in La2/3(Ca0.6Ba0.4)1/3Mn1-xVxO3 lowers the Curie temperature TC and the metal–insulator transition temperature TMI; (2) there exists the evident difference between the TC and the TMI for different V substitution ratio; (3) the low-temperature tunneling magnetoresistance and maximum magnetoresistance near Tc increase with the enhancement of V-doping content. Based on the tunneling magnetoresistance model and the percolation model near Curie temperature, the experimental results are explained well.
Authors: Zhen Zhen Weng, Zhi Gao Huang, Wen Xiong Lin
Abstract: The interatomic exchange interactions and the electronic structure of Co-doped ZnO with and without oxygen vacancy have been investigated by the first-principles calculations based on density functional theory. It is found that the oxygen vacancy can strengthen the ferromagnetic exchange interaction between Co atoms and might be available for carrier mediation. The oxygen vacancy near to the Co atoms is more favorable for the ferromagnetic ground state.
Authors: Qing Ying Ye, Shui Yuan Chen, Ke Hua Zhong, Xiu Lai Chen, Zhi Gao Huang
Abstract: Based on the Monte-Carlo simulation and fast Fourier transformation-micro-magnetism (FFTM) method, magnetic properties with different parameters for the 4×4 Magnetic Quantum Dot Arrays (QDA) were studied. The calculating processes show that the same calculated results can be obtained by both methods above. But the FFTM method can save much time in obtaining results, which suggest that the method be employed to study more complex systems. The calculated results indicate that there exists obvious difference in the magnetic hysteresis loops with different temperatures, which can be well explained by considering the relationship between the easy-magnetization axis and the organization anisotropy of the QDA system. Furthermore, saturation field (Hs) increases with the dipolar interaction increasing, which is attributed to the competition between dipolar energy (ED) and Zeeman energy (EZ). The calculated results can fit the experimental results very well. Besides, it is found that the dipolar interaction constant D has a great influence on magnetic properties.
Authors: Shui Yuan Chen, Zhi Gao Huang, Heng Lai, Rongquan Gai, Feng Ming Zhang, You Wei Du
Abstract: Ferromagnetic (FM) La2/3(Ca0.6Ba0.4)1/3MnO3 and antiferromagnetic (AFM) NiO nanoparticles were synthesized using sol-gel method, respectively. La2/3(Ca0.6Ba0.4)1/3MnO3 (1 mol)/ x NiO (x= 0, 0.05 and 0.15mol) composites with the coated NiO were prepared. The experimental results indicate that, both phases of LCBMO and NiO coexist clearly in the composites and the sizes of the NiO nanoparticles in the intergranular region between the LCBMO particles are very small; the interface of NiO influences evidently the value of MR and it is found that the tunneling MR for x=0.05 is the largest in three samples. The magnetoresistance behavior has been explained by two-level model of tunneling magnetoresistance and percolation model well.
Authors: Zhi Gao Huang, Qian Feng, Yong Shen Li, Feng Ming Zhang, You Wei Du
Abstract: In this paper, the spin configuration and the configurational anisotropy of the clusters were studied by Monte Carlo simulations. An easy magnetization directions and a configurational anisotropy were found for the clusters using the hysteresis and spin configurations in different magnetization processes, and the simulated natural angle and energy distribution. It is considered that the configurational anisotropy is mainly attributed to the non-uniformity in spin configurations.
Authors: Zhi Gao Huang, Yingbin Lin, Yan Min Yang, Feng Ming Zhang, You Wei Du
Abstract: In this paper, based on 4×4 matrix method, we present theoretical calculations of the polar magneto-optical Kerr effect for Co/Pt and MnBi multilayered films, and NixSiO2(1-x) granular films. The calculated results indicate that, (1) the simulated Kerr spectra as a function of photo-energy are in good agreement with experimental ones; (2) the maxima and the periodical and damped oscillation appear in the Kerr spectra curve with the magnetic thickness, which is important for design of the material in the future; (3) the structure of interfacial layer affect greatly the Kerr spectra, which is significant for the processing of magneto-optical material.
Authors: Qian Feng, Qing Ying Ye, Zhen Zhen Wen, Li Qin Jiang, Zhi Gao Huang, Feng Ming Zhang, You Wei Du
Abstract: A ferromagnetic monolayer with competing long-range dipolar interaction, short-range interaction and magnetic uniaxial anisotropy is studied using Monte Carlo simulation. Striped domain patterns are found and reveal the microstructure of the magnetization transition at the ground state via the competing between dipolar interaction and uniaxial anisotropy. We present the finite temperature phase diagram and find a temperature-induced magnetization reorientation from out-of-plane to in-plane phase. The influence of the various interactions on the structure of the striped phase and reorientation behavior has been discussed.
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