Orientation and thickness dependence of magnetization at the interfaces of highly spin-polarized manganite thin films
Orientation and thickness dependence of magnetization at the interfaces of highly spin-polarized manganite thin films
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DOI：
10.1103/physrevb.79.104417
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发表时间：
2009-03-01
影响因子：
3.7
通讯作者：
Suzuki, Y.
中科院分区：
文献类型：
--
作者：
Chopdekar, Rajesh V.;Arenholz, Elke;Suzuki, Y.
我们研究了（001）、（110）和（111）取向的La_（0.7）Sr_（0.3）MnO_3薄膜表面的磁性。La0.7Sr0.3MnO3薄膜的自旋极化在所有的表面和界面上都没有被抑制，但对外延应变状态和衬底取向都非常敏感。通过使用软X射线光谱，（001）-，（110）-和（111）-取向的La 0.7Sr 0.3MnO 3/SrTiO 3界面的磁性进行了研究，并进行了比较，体磁强计和电阻率测量。（110）和（111）取向的La0.7Sr0.3MnO3/SrTiO 3界面的磁化强度作为厚度的函数更像体，而（001）取向的La0.7Sr0.3MnO3/SrTiO 3界面处的磁化强度在低于20 nm的层厚度时被显著抑制。这些发现与La0.7Sr0.3MnO3薄膜的双轴应变状态有关;对于给定的薄膜厚度，（001）La0.7Sr0.3MnO3的四方畸变严重影响磁化强度，而（111）取向薄膜的三角畸变和（110）取向薄膜的单斜畸变影响较小。这些观察结果提供的证据表明，表面磁化，从而自旋极化强烈依赖于晶体表面取向以及外延应变。
We have probed the nature of magnetism at the surface of (001)-, (110)-, and (111)-oriented La0.7Sr0.3MnO3 thin films. The spin polarization of La0.7Sr0.3MnO3 thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001)-, (110)-, and (111)-oriented La0.7Sr0.3MnO3/SrTiO3 interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110)- and (111)-oriented La0.7Sr0.3MnO3/SrTiO3 interfaces is more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La0.7Sr0.3MnO3/SrTiO3 interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La0.7Sr0.3MnO3 films; for a given film thickness it is the tetragonal distortion of (001) La0.7Sr0.3MnO3 that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depend strongly on the crystal surface orientation as well as epitaxial strain.