| M-type barium ferrite(Ba Fe12O19,Ba M)is widely used in microwave devices and magnetic recording devices because of its high uniaxial anisotropy,low ferromagnetic resonance linewidth and gyromagnetism.Compared with the commonly used magnetic films,the ordered magnetic array has higher natural resonance frequency and remanence ratio due to its unique structure,which makes it a potential candidate in the next generation of high-frequency,miniaturized and self biased components.At present,there are few researches focus on the relationship between the magnetic properties and the structure of Ba M nano-array and its preparation.This paper will focus on the research of micromagnetic simulation and preparation of Ba M nano-array.The work contents are shown as follows:(1)Studying the reversal magnetization and resonance characteristics of cylinder-shaped Ba M nanopillars and their arrays.The results show that there are two reversal modes in Ba M: quasi-uniform reversal magnetization and reversal domain formation and expansion.The simulation results display that there are two main resonance modes in the cylinder-shaped Ba M: "body resonance mode" and "edge resonance mode".The edge effect depth of the "edge resonance mode" is about 50 nm.At the same time,in the cylinder-shaped Ba M array,the natural resonance frequency of 4.12-8.75 GHz can be regulated by adjusting the diameter of the nanocolumn(50-110 nm)and the space(30-190 nm).This phenomenon shows that the strong interaction field between the nano-column in the array structure has a great influence on the resonance frequency.Therefore,the working frequency of the device can be regulated by changing the array structure.(2)Studying the reversal magnetization and resonance characteristics of conical-shaped Ba M and its array structure are studied.The results show that: firstly,there are two kinds of reversal modes,quasi uniform reversal magnetization and reversal domain formation and expansion;secondly,the natural resonance of conical-shaped Ba M is also affected by the size.When the diameter of the nano conical increases from 50 nm to 290 nm,the resonance peaks increase from 2 to 4,and the resonance frequency of the main peak decreases by 3.13 GHz.At the same time,it is found that due to the special structure,its resonance distribution has obvious stratification phenomenon.Many resonance peaks appeared in the magnetic spectrum,which makes it a potential application in the field of high frequency noise suppression.The resonant frequency of the array system can be regulated over 4 GHz with the change of the distance between nano cones.In addition,the intensity of the interaction field between the nano cones is sensitive to the changing of distance,and the intensity is m T level.According to the simulation results of conical-shaped and cylinder-shaped array,the strong interaction field between particles in array structure can not be ignored and received attention.(3)Conical-shaped and cylinder-shaped Ba M arrays were successfully fabricated on Al2O3 substrate by pulse laser deposition and ultra-thin porous anodic alumina template.The effects of template aperture and substrate temperature on array morphology and magnetism were investigated.The results show that the prepared particles have good size uniformity and c-axis orientation,and the remanence ratio of Ba M nano-array is increased with the substrate temperature.The results of first-order inversion curve display that the cylinder-shaped Ba M array prepared at 700 ? has better particle uniformity,and the distribution of coercivity and interaction force of the array prepared at 900 ? are relatively dispersed.Consequently,the template pore size and substrate temperature have great influence on the morphology and magnetic properties of the array system. |
PDF Full Text Request