王晓丹
,
赵志伟
,
王静雅
,
徐军
,
Gilbert Bourdet
,
J.-C. Chanteloup
无机材料学报
doi:10.3321/j.issn:1000-324X.2008.01.024
采用热键合技术制备了Yb:Y3Al5O12/Y3Al5O12(Yb:YAG/YAG)复合晶体,对复合晶体进行了结构表征和键合质量检测.利用光学显微镜和扫描电镜观察了复合晶体横截面的形貌;在偏光显微镜下观察键合区域的应力,利用干涉条纹来表征复合晶体的光学均匀性;通过红外透过光谱的测量来检测复合晶体的键合质量.实验结果表明:热键合技术制备的Yb:YAG/YAG复合晶体键合界面处无界面缺陷,不存在复合界面空间过渡层,光学均匀性良好.
关键词:
Yb:YAG/YAG
,
键合质量
,
应力
,
光学均匀性
,
热键合
J.Q. Yu
,
Y. Zhou
,
B.C. Cai and X.L. Zhao Information Storage Research Center
,
Research Lab of Thin Films and Microfabrication Technology
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China
金属学报(英文版)
Giant magneto-impedance effect (MI) in thin films with longitudinal magnetic anisotropy is studied theoretically. The effective permeability of films as a function of external magnetic field Ha, anisotropy field and other parameters of films is presented using Landau - Lifshitz- Gilbert theory. The theoretical results agree well with experimental ones, which show a strong dependence of the impedance on the applied magnetic field.
关键词:
magneto-impedance effect
,
null
,
null
,
null
Journal of Magnetism and Magnetic Materials
Micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation are presented to study spin-polarized current induced magnetization switching in a symmetric nanoring-shaped magnetic tunnel junctions. The results show that in an a noring with an intermediate eccentric distance S, the critical switching voltage V(C) reaches the minimum whose magnitude is less than half of the voltage for a symmetric nanoring. In addition to the spin-transfer torque, the current induced Ampere ere. field is found to play a crucial part in the switching process. Analysis is given to explain the existence of such an energy valley that leads to the minimal voltage. (C) 2009 Elsevier B.V. All rights reserved.
关键词:
Spin torque;Current induced magnetization switching;Micromagnetic;simulation
Solid State Communications
A double-domain model with long-range dipole-dipole interaction is proposed to investigate the self-oscillation of magnetization in nano-magnetic systems driven by self-controlled spin-polarized current. The dynamic behavior of magnetization oscillation is calculated by a modified Landau-Lifshitz-Gilbert equation in order to evaluate the effects of the long-range dipole-dipole interaction. While the self-oscillation of magnetization can be maintained substantially, several self-oscillation regions are experienced as the dipole-dipole interaction increases gradually. (C) 2011 Elsevier Ltd. All rights reserved.
关键词:
Magnetic metals;Spin-polarized current;Self-oscillation;wall motion;spin-waves;driven;ferromagnets
杨兵初
,
舒畅
,
邓联文
,
伍益
,
李文芳
功能材料
基于Landau-Lifshitz-Gilbert方程、Bruggeman有效媒质理论及纳米颗粒膜的电输运和介电理论,通过计算磁性纳米颗粒膜的有效磁导率、有效介电常数、计算分析饱和磁化强度、各向异性场、电导率和阻尼系数对纳米颗粒膜吸波性能的影响.结果表明,饱和磁化强度、各向异性场、电导率和阻尼系数均对纳米颗粒膜的微波吸收特性产生显著影响,通过调控纳米颗粒膜的电磁特性可以有效提高其吸波性能,可以应用于薄层吸波材料的设计中.
关键词:
磁性纳米颗粒膜
,
有效媒质理论
,
LLG方程
,
微波吸收
Physical Review B
The magnetic hysteresis and its area for two-dimensional nanomagnets with precessional magnetization reversal, driven by ac magnetic field of frequency f and amplitude H-0, are investigated by numerically solving the Landau-Lifshitz-Gilbert equation. Irregular hysteresis loops are observed when f is low and H-0 is high, indicating the significant contribution of nonadiabatic precession to the magnetization reversal. The frequency dispersion of hysteresis area A(f) shows the double-peaked pattern with the low-f peak caused by the precessional magnetization reversal and the high-f peak originating from the quasichaotic oscillations of the spin precession. The power-law scaling behavior of the hysteresis dispersion, i.e., A proportional to H(0)(lambda)f(beta) with exponents lambda=0.60 and beta=0.50, is observed in the low-f range limit. We present the one-parameter dynamic scaling on the low-f hysteresis dispersions over a broad range of H-0, demonstrating the scalability of the hysteresis dispersion and thus the existence of the unique characteristic time for magnetization reversal process in nanomagnets, given the field amplitude H-0.
关键词:
precessional magnetization reversal;self-organized criticality;model;spin systems;films;field
Journal of Physics-Condensed Matter
The mechanism of magnetization reversal in single-domain ferromagnetic particles is of interest in many applications, in most of which losses must be minimized. In cancer therapy by hyperthermia the opposite requirement prevails: the specific loss power should be maximized. Of the mechanisms of dissipation, here we study the effect of Neel relaxation on magnetic nanoparticles unable to move or rotate and compare the losses in linearly and circularly polarized fields. We present exact analytical solutions of the Landau-Lifshitz equation as derived from the Gilbert equation and use the calculated time-dependent magnetizations to find the energy loss per cycle. In frequencies lower than the Larmor frequency, linear polarization is found to be the better source of heat power, at high frequencies (beyond the Larmor frequency) circular polarization is preferable.
关键词:
therapy
Journal of Applied Physics
A direct inter-conversion between conduction electron spin-current and spin wave spin-current has been experimentally realized in Pt/Y(3)Fe(5)O(12) and Pt/Y(3)Fe(5)O(12)/Pt heterostructures [Y. Kajiwara et al., Nature 464, 262 (2010)]. We investigate the dynamics of this inter-conversion in an in-plane spiral magnet with the nearest-neighboring interaction and Dzyaloshinskii-Moriya interaction, using the modified Landau-Lifshitz-Gilbert equation. The calculations indicate that an unattenuated conical spin wave in the spiral magnet can be excited by a spin-torque representing a conduction-electron spin-current. The substantial role of the Dzyaloshinskii-Moriya interaction in stabilizing such unattentuated spin wave transmission is revealed. In addition, the influences of the spin-torque term and damping coefficient on the stability of the spin wave transmission are discussed. (C) 2011 American Institute of Physics. [doi:10.1063/1.3631827]
关键词:
classical heisenberg-model;ferromagnets;mnsi;phase;order
