Large negative uniaxial magnetic anisotropy in highly distorted Co-ferrite thin films
Large negative uniaxial magnetic anisotropy in highly distorted Co-ferrite thin films
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高畸变钴铁氧体薄膜中的大负单轴磁各向异性
DOI：
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发表时间：
2019
影响因子：
4
通讯作者：
H. Yanagihara
中科院分区：
文献类型：
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作者：
T. Tainosho;J. Inoue;S. Sharmin;M. Takeguchi;E. Kita;H. Yanagihara
研究了反应溅射在MgAl2O4(001) （MAO）表面生长的外延钴铁氧体（CFO）薄膜的应变诱导磁各向异性（MA）。由于衬底和薄膜之间的晶格不匹配，这些薄膜经历了很大的四方压缩应变，导致四方性高达- 0.04。扫描透射电镜观察结合快速傅里叶变换分析表明，晶格畸变随薄膜厚度的增加而单调放松。与MgO（001）衬底上的CFO（001）膜不同，CFO和MAO之间的界面处存在磁增强层。通过磁转矩测量，在300 K时，最薄的12.9 nm薄膜的负单轴MA能量为−5.9 MJ/m3。随着薄膜厚度的增加，非拟合弛豫引起的诱导单轴各向异性减小。通过拟合线确定的不同厚度和不同四方性的薄膜的磁弹性常数为0.15±0.01 GJ/m3。这一结果与主体0.14 GJ/m3的值一致，并表明CFO的现象学ME理论框架适用于广泛的四方性，至少可达- 0.04。我们的研究结果还表明，CFO薄膜的失配工程在诱导增强单轴MA方面具有很大的潜力。研究了反应溅射在MgAl2O4(001) （MAO）表面生长的外延钴铁氧体（CFO）薄膜的应变诱导磁各向异性（MA）。由于衬底和薄膜之间的晶格不匹配，这些薄膜经历了很大的四方压缩应变，导致四方性高达- 0.04。扫描透射电镜观察结合快速傅里叶变换分析表明，晶格畸变随薄膜厚度的增加而单调放松。与MgO（001）衬底上的CFO（001）膜不同，CFO和MAO之间的界面处存在磁增强层。通过磁转矩测量，在300 K时，最薄的12.9 nm薄膜的负单轴MA能量为−5.9 MJ/m3。随着薄膜厚度的增加，非拟合弛豫引起的诱导单轴各向异性减小。用拟合线确定了不同厚度的薄膜和不同四边形的磁弹性（ME）常数。
The strain induced magnetic anisotropy (MA) of epitaxial Co-ferrite (CFO) thin films grown on MgAl2O4(001) (MAO) by reactive sputtering was studied. These films underwent large tetragonal compressive strain due to the lattice mismatch between the substrates and films, resulting in tetragonalities of up to −0.04. Scanning transmission electron microscopy observation combined with fast Fourier transform analysis revealed that the lattice distortion monotonically relaxed with the increasing film thickness. Unlike the CFO(001) films on MgO(001) substrates, a magnetically enhanced layer exists at the interface between CFO and MAO. A large negative uniaxial MA energy of −5.9 MJ/m3 was confirmed for the thinnest film of 12.9 nm at 300 K by magneto-torque measurements. The induced uniaxial anisotropy decreased with the increasing film thickness owing to misfit relaxation. The magneto-elastic (ME) constant, which was determined by a fitting line for films with different thicknesses and therefore different tetragonalities, was 0.15±0.01 GJ/m3. This result is consistent with the value of 0.14 GJ/m3 for the bulk and suggests that the framework of the phenomenological ME theory for CFO is valid for a wide range of tetragonalities, at least up to −0.04. Our results also indicate that the misfit engineering of CFO thin films has great potential in inducing enhanced uniaxial MA.The strain induced magnetic anisotropy (MA) of epitaxial Co-ferrite (CFO) thin films grown on MgAl2O4(001) (MAO) by reactive sputtering was studied. These films underwent large tetragonal compressive strain due to the lattice mismatch between the substrates and films, resulting in tetragonalities of up to −0.04. Scanning transmission electron microscopy observation combined with fast Fourier transform analysis revealed that the lattice distortion monotonically relaxed with the increasing film thickness. Unlike the CFO(001) films on MgO(001) substrates, a magnetically enhanced layer exists at the interface between CFO and MAO. A large negative uniaxial MA energy of −5.9 MJ/m3 was confirmed for the thinnest film of 12.9 nm at 300 K by magneto-torque measurements. The induced uniaxial anisotropy decreased with the increasing film thickness owing to misfit relaxation. The magneto-elastic (ME) constant, which was determined by a fitting line for films with different thicknesses and therefore different tetragon...