面外取向的(BiTm)_(3)(GaFe)_(5)O_(12)磁光单晶薄膜制备及取向机理分析  

Preparation and orientation mechanism analysis of(BiTm)_(3)(GaFe)_(5)O_(12) magneto-optical single crystal film with out-of-plane orientation

作　　者：杨雪[1] 杨青慧[1] 张怀武[1] 文岐业[1] 白飞明[1] 钟智勇[1] 张鼎 黄建涛 Yang Xue;Yang Qing-Hui;Zhang Huai-Wu;Wen Qi-Ye;Bai Fei-Ming;Zhong Zhi-Yong;Zhang Ding;Huang Jian-Tao(School of Electronic Science and Engineering,University of Electronic Science and Technology of China,Chengdu 611731,China)

机构地区：[1]电子科技大学电子科学与工程学院,成都611731

出　　处：《物理学报》2021年第10期296-303,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2016YFA0300801);国家自然科学基金(批准号:51472046,51272036,51002021,61131005);国家重大科学仪器设备开发项目(批准号:51827802)资助的课题.

摘　　要：铋取代石榴石(Bi:YIG)薄膜具有较大的比法拉第旋角,且可通过调控其易磁化轴垂直于薄膜表面和降低材料饱和磁化强度,使其可工作在较小外加磁场下,进而满足磁光器件小型化、节能化的发展需求.本文基于对石榴石薄膜磁各向异性的理论分析,采用液相外延(liquid-phase epitaxy,LPE)法在钆镓石榴石(gadolinium gallium garnet,GGG)基底上制备了单晶(BiTm)_(3)(GaFe)_(5)O_(12)膜,并研究了其磁各向异性性能.研究发现,当外延膜厚度大于1μm时,形状各向异性对磁各向异性产生的影响可以忽略;随着生长温度的上升,进入薄膜组分的Bi^(3+)离子数量逐渐减少,薄膜晶格常数逐渐减小,薄膜的受力状态从压应力状态逐渐变为张应力;相较于生长感生各向异性,应力诱导的各向异性在磁各向异性的变化中占主导地位.(BiTm)_(3)(GaFe)_(5)O_(12)膜的Verdet常数为11.8×10^(4) rad/Tm@1064 nm,是常用磁光材料TGG的3000倍;其外加工作磁场小于200 Oe,有利于实现磁光器件的小型化和薄膜化.Liquid-phase epitaxy(LPE)is one of the best techniques for the preparation of single crystal garnet films.However,the specific Faraday rotation angle of Yttrium iron garnet(YIG)is small,and its easy magnetization axis is parallel to the film surface.The YIG requires a large external saturation field,which cannot meet the development needs of magneto-optical devices.It is found that Bi-substituted YIG(Bi:YIG)film has a larger specific Faraday angle.By adjusting the easy magnetization axis of Bi:YIG perpendicular to the film surface,the saturation magnetization of Bi:YIG can be reduced,so that it can work under a small external magnetic field.This meets the development needs of miniaturization and energy saving of magneto-optical device.The saturation magnetization of garnet film can be effectively reduced by substituting Ga^(3+)for YIG crystal,mainly for Fe3+at the 24d position of its tetrahedron.And the lattice constants of Gd_(3)Ga_(5)O_(12)(GGG)and YIG are 1.2383 nm and 1.2376 nm,respectively.However,the radius of Bi^(3+)(10.8 nm)is larger than that of Y^(3+)(9.0 nm),the lattice mismatch of garnet film increases with the incorporation of Bi^(3+).In order to neutralize the lattice expansion caused by Bi^(3+),Tm^(3+)(8.69 nm)with a radius smaller than that of Y^(3+)(9.0 nm)is selected.Based on the theoretical analysis of the magnetocrystalline anisotropy of garnet film,(BiTm)_(3)(GaFe)_(5)O_(12) monocrystalline films with different growth temperatures and different thickness values are grown by LPE on GGG(111)substrates.The experimental results show that when the thickness of epitaxial film is greater than 1μm,the influence of shape anisotropy on magnetocrystalline anisotropy can be ignored.With the increase of growth temperature,the substitution number of Bi^(3+)ions decreases gradually,the lattice constant of epitaxial film decreases gradually,and the lattice mismatch first decreases and then increases.Then,the state of compressive stress gradually changes into that of tensile stress.Compared with growth-induc

关 键 词：液相外延 磁各向异性 晶格失配 

分 类 号：O469[理学—凝聚态物理]