Anisotropic spin-density distribution and magnetic anisotropy of strained La1-xSrxMnO3 thin films: angle-dependent x-ray magnetic circular dichroism
Anisotropic spin-density distribution and magnetic anisotropy of strained La1-xSrxMnO3 thin films: angle-dependent x-ray magnetic circular dichroism
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DOI：
10.1038/s41535-018-0077-4
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发表时间：
2018-01-26
影响因子：
5.7
通讯作者：
Fujimori, Atsushi
中科院分区：
文献类型：
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作者：
Shibata, Goro;Kitamura, Miho;Fujimori, Atsushi
铁磁薄膜的磁各向异性是由基底外延应变引起的，主要表现为轨道磁矩和自旋极化电子空间分布的应变诱导各向异性。然而，用x射线线性二色性（XLD）研究的铁磁金属La1-xSrxMnO3 （LSMO）薄膜在拉伸和压缩外延应变下的优先轨道占位一直是面外的，因此与磁各向异性无关。为了解开这一谜团，我们利用角度相关的x射线磁圆二色性（XMCD）直接探测了应变作用下LSMO薄膜中自旋极化电子的优先轨道占位。自旋密度分布的各向异性发现，拉伸应变为面内，压缩应变为面外，与观测到的磁各向异性一致。XLD中普遍存在的面外轨道优先占位现象是由于表面磁死层中同时存在自旋向上和自旋向下的面外轨道。
Magnetic anisotropies of ferromagnetic thin films are induced by epitaxial strain from the substrate via strain-induced anisotropy in the orbital magnetic moment and that in the spatial distribution of spin-polarized electrons. However, the preferential orbital occupation in ferromagnetic metallic La1-xSrxMnO3 (LSMO) thin films studied by x-ray linear dichroism (XLD) has always been found out-of-plane for both tensile and compressive epitaxial strain and hence irrespective of the magnetic anisotropy. In order to resolve this mystery, we directly probed the preferential orbital occupation of spin-polarized electrons in LSMO thin films under strain by angle-dependent x-ray magnetic circular dichroism (XMCD). Anisotropy of the spin-density distribution was found to be in-plane for the tensile strain and out-of-plane for the compressive strain, consistent with the observed magnetic anisotropy. The ubiquitous out-of-plane preferential orbital occupation seen by XLD is attributed to the occupation of both spin-up and spin-down out-of-plane orbitals in the surface magnetic dead layer.