Substrate induced magnetic anisotropies and magneto-optical response in YIG nanosized epitaxial films on NdGG(111)
Substrate induced magnetic anisotropies and magneto-optical response in YIG nanosized epitaxial films on NdGG(111)
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NdGG(111) 上 YIG 纳米级外延薄膜中的基底感应磁各向异性和磁光响应
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发表时间：
2018
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通讯作者：
N. Sokolov
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作者：
B. Krichevtsov;V. Bursian;S. Gastev;A. Korovin;L. Lutsev;S. Suturin;K. Mashkov;M. Volkov;N. Sokolov
用激光分子束外延方法在Nd 3Ga 5 O 12衬底上生长了Y3 Fe 5 O 12纳米外延薄膜。磁光极性克尔效应、铁磁共振和自旋波传播测量表明，与YIG/GGG系统相比，与应力相关的各向异性场具有相反的符号。这导致了有效磁化强度的显著降低，这为获得具有垂直磁化强度的YIG薄膜以利用前向体自旋波开辟了前景。纵向磁光克尔效应磁强计揭示了一个大的贡献二次磁化条款到介电常数张量在光学频率。这种效果强烈增加，随着温度的降低，并解释了交换耦合到Fe离子的界面Nd离子的磁化。随着氧化物自旋电子学和磁电子学的蓬勃发展，基于钇铁石榴石（YIG，Y3 Fe 5 O 12）薄膜的纳米异质结材料引起了人们的广泛关注。为了实现自旋波包的有效数据传输和处理，需要在GHz频率下具有低磁损耗的高质量异质结构。近年来，人们对钆镓石榴石（GGG，Gd_3Ga_5O_（12））衬底上外延生长的YIG薄膜的静态和动态磁性能进行了大量的研究。用激光分子束外延（LMBE）生长的纳米YIG薄膜具有高的结晶质量、窄线铁磁共振（FMR）和低的自旋波阻尼9，。假设阻尼参数α是共振频率的线性函数，在参考文献10中计算出α = 6.15×10。另一方面，在低温（700 °C）下生长的纳米尺寸的YIG膜中的自旋波传播的直接测量表明阻尼参数可以更低（< 3.6 Ω 10）。在没有外磁场的情况下，YIG / GGG（111）薄膜中的磁化位于平面内，这是由于退磁场Hd = 4 π Ms-1.2 - 1.5 kOe被磁弹性相互作用14，.在前向体自旋波器件中，面外磁化是必要的，18并且需要强永磁体。避免笨重的磁铁的方法是建造
Nanosized Y3Fe5O12 epitaxial films have been grown on Nd3Ga5O12 substrates using laser molecular beam epitaxy method. Magneto-optical polar Kerr effect, ferromagnetic resonance and spin wave propagation measurements show that the stress-related anisotropy field has an opposite sign, compared to that in the YIG/GGG systems. This leads to a considerable decrease of the effective magnetization that opens a perspective to get YIG films with perpendicular magnetization for utilizing forward volume spin waves. Longitudinal magnetooptical Kerr effect magnetometry reveals a large contribution of quadratic in magnetization terms into dielectric permittivity tensor at optical frequencies. This effect strongly increases with temperature decrease and is explained by magnetization of the interface Nd ions that are exchange coupled to the Fe ions. The nanoscale heterostructures based on yttrium iron garnet (YIG, Y3Fe5O12) films attract much attention nowadays owing to the intense development of oxide spintronics and magnonics , , , . For the realization of effective data transmission and processing by spin wave packets, one needs high quality heterostructures with low magnetic losses at GHz frequencies. A great number of recent studies has been dedicated to investigation of epitaxial growth, static and dynamic magnetic properties of YIG layers epitaxially grown onto gadolinium gallium garnet (GGG, Gd3Ga5O12) substrates. The nanosized YIG films grown by laser molecular beam epitaxy (LMBE) exhibit high crystalline quality , , , , narrow-line ferromagnetic resonance (FMR) and low spin wave damping 9 , , , , . Assuming that the damping parameter α is linear function of the resonance frequency, in Ref. 10 it was calculated that α = 6.15×10. On the other hand, the direct measurement of spin wave propagation in nanosized YIG films grown at low temperatures (700 °C) shows that the damping parameter can be even lower (< 3.6⋅10) . In the absence of external magnetic field, the magnetization in YIG / GGG(111) films lies inplane due to the demagnetizing field Hd = 4πMs ≈ (1.2 – 1.5) kOe reinforced by the magnetic anisotropy Ha ≈ -1 kOe (4πMeff = 4πMs – Ha ≈ 2 kOe) induced by the magnetoelastic interactions 14 ,. In the forward volume spin wave devices the out-of-plane magnetization is necessary , , 18 and a strong permanent magnet is required. The way to avoid the bulky magnet, is to construct