Magnetization reversal in YIG/GGG(111) nanoheterostructures grown by laser molecular beam epitaxy.
Magnetization reversal in YIG/GGG(111) nanoheterostructures grown by laser molecular beam epitaxy.
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DOI：
10.1080/14686996.2017.1316422
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发表时间：
2017
影响因子：
5.5
通讯作者：
Sokolov NS
中科院分区：
文献类型：
--
作者：
Krichevtsov BB;Gastev SV;Suturin SM;Fedorov VV;Korovin AM;Bursian VE;Banshchikov AG;Volkov MP;Tabuchi M;Sokolov NS
在Gd3Ga5O12，GGG(Gd3Ga5O12，GGG)111取向衬底上，采用激光分子束外延技术，在700~1000℃的生长温度范围内，生长了(4~20 nm)Y3Fe5O12(YIG)薄层。这些层具有原子平坦的阶梯状表面形态，台阶高度为1.8？，这是YIG(111)表面的特征。当生长温度从700℃升高到1000℃时，梯田变宽，生长逐渐从层层向阶梯流态转变。电子衍射和X射线衍射研究表明，YIG晶格与GGG具有共取向和横向假象，且垂直于表面有较小的菱面体形变。用磁矩、磁光极化和纵向克尔效应(MOKE)和X射线磁性圆二色谱(XMCD)研究了不同磁场方向的磁化反转。这些方法和铁磁共振研究表明，在零磁场下，由于形状各向异性和感应各向异性，磁化强度位于薄膜平面。矢量MOKE研究揭示了平面内易磁化轴的存在。面内磁化反转是通过可逆旋转和突然不可逆磁化跳跃相结合的方式发生的，而不可逆磁化突变是由磁化壁形核和传播引起的。发生翻转的磁场取决于外加磁场和易磁化轴之间的夹角，并且可以用修正的Stoner-Wohlfarth模型描述，该模型考虑了磁化壁能对磁场的依赖关系。用XMCD研究了四面体和八面体磁性Fe3+亚晶格的磁化曲线。
Thin (4–20 nm) yttrium iron garnet (Y3Fe5O12, YIG) layers have been grown on gadolinium gallium garnet (Gd3Ga5O12, GGG) 111-oriented substrates by laser molecular beam epitaxy in 700–1000 °C growth temperature range. The layers were found to have atomically flat step-and-terrace surface morphology with step height of 1.8 Å characteristic for YIG(111) surface. As the growth temperature is increased from 700 to 1000 °C the terraces become wider and the growth gradually changes from layer by layer to step-flow regime. Crystal structure studied by electron and X-ray diffraction showed that YIG lattice is co-oriented and laterally pseudomorphic to GGG with small rhombohedral distortion present perpendicular to the surface. Measurements of magnetic moment, magneto-optical polar and longitudinal Kerr effect (MOKE), and X-ray magnetic circular dichroism (XMCD) were used for study of magnetization reversal for different orientations of magnetic field. These methods and ferromagnetic resonance studies have shown that in zero magnetic field magnetization lies in the film plane due to both shape and induced anisotropies. Vectorial MOKE studies have revealed the presence of an in-plane easy magnetization axis. In-plane magnetization reversal was shown to occur through combination of reversible rotation and abrupt irreversible magnetization jump, the latter caused by domain wall nucleation and propagation. The field at which the flip takes place depends on the angle between the applied magnetic field and the easy magnetization axis and can be described by the modified Stoner–Wohlfarth model taking into account magnetic field dependence of the domain wall energy. Magnetization curves of individual tetrahedral and octahedral magnetic Fe3+ sublattices were studied by XMCD.