摘要
用磁畴组态能量比较方法,导出外磁场场强为H时的铁磁微晶(即尺寸小于L_0的铁磁性单晶体;L_0为外磁场H为零时,单畴粒子尺寸的临界值)临界尺寸表达式,给出了与微晶尺寸L_s相关的矫顽强度H(L_s);并以SmCo_5材料为例,对H(L_s)做了定量估计。得出:在L_s小于L_0而大于L_c时,微晶也与尺寸大于L_0o的粒子类似,反磁化经历多畴过程;当L_s≤L_c时,反磁化才按Stoner-Wohlforth机制进行。认为用RECo_5材料制做具有_MH_C=2k/M_s的高级磁体是可能的。
The expression of critical size of ferromagnetic microcrystal when the external magnetic field intensity is H is derived by means of comparing energies in different states of domain structure. The ferromagnetic microcrystal here means a single ferromagnetic crystal of which the size is smaller than L0, and L0 is the critical value of the size of single-domain particles if the external magnetic field intensity H=0. Also, the coercive strength H(Ls) relating to the size of microcrystal L, is given and quantitatively evaluated with the material SmCo5 as an instance. It is thus concluded that if L0>Ls>Lc, the antimagneti-zation of microcrystal will be subjected to a multidomain process just like the particles of a size greater than L0, only if Ls≤Lc, the antimagnetization will carry on in accordance with the Stoner-Wohlforth mechanism (Lc is the max size of microcrystal if H(Ls)=MHcth). It is suggested that the material RECo5 is available to make a high-grade magnet with MHc =2k/Ms.
关键词
铁磁微晶
矫顽力
磁化机制
magnetization mechanism, coercive force, ferromagnetic microcrystal.
