报告人：John Q. Xiao
Department of Physics and AstronomyUniversity of Delaware, DE 19716
报告题目：磁性纳米线阵列的微波性能和记忆效应
地点： 曹光彪大楼三楼326会议室
时间： 2011年7月26日(周二)上午九点
邀请人：严密 教授
Abstract：
Magnetic nanowire array embedded in an insulating Al2O3 matrix can be conveniently fabricated by electrochemically depositing magnetic materials into anodized alumina templates (AAT). By controlling the parameters in anodizing processes, the diameter of each nanowire and the separation between nanowires can vary from a few tens to hundreds of nanometers. With careful preparations of AAT and magnetic nanowires, we achieved samples with uniform distribution and strong dipolar interaction. These samples reveal novel static and microwave properties. First we demonstrated that the natural FMR of Ni90Fe10 nanowire array can be tailored continuously from 8.2 to 11.7 GHz by choosing different remanent state. The observed phenomena can be explained with a theoretical model based on magnetostatic interaction among nanowires. Second interesting phenomenon caused by the dipolar interaction is the “memory effect”, referring to the phenomenon that the magnetic nanowire array “memorizes” the maximum negative field it was exposed to in terms of its remanent magnetization. The “memory effect” offers a new solution to the ultra strong magnetic pulse detection. Finally, we will also discuss the permeability spectra of these nanowires as high frequency soft magnetic materials.
材料系
2011-7-25
