Effect of strain on magnetic and orbital ordering of LaSrCrO3/LaSrMnO3 heterostructures
Effect of strain on magnetic and orbital ordering of LaSrCrO3/LaSrMnO3 heterostructures
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DOI：
10.1103/physrevb.101.064420
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发表时间：
2020-02-19
影响因子：
3.7
通讯作者：
Kumah, Divine P.
中科院分区：
文献类型：
--
作者：
Koohfar, Sanaz;Georgescu, Alexandru B.;Kumah, Divine P.
我们利用体磁力测定、软 X 射线磁谱、第一性原理密度泛函理论、高分辨率电子显微镜和 X 射线衍射研究了应变和薄膜厚度对 LaSrCrO3 (LSCO)/LaSrMnO3 (LSMO) 异质结构的轨道和磁性能的影响。我们观察到铁磁 LSMO 层和 LSCO 间隔件之间磁矩的反平行排序，导致薄如两个晶胞的 LSMO 层的 LSCO/LSMO 异质结构具有应变无关的铁磁基态。随着 LSMO 厚度的增加，净铁磁状态得以维持，然而，每个 Mn 的平均磁矩被发现取决于基底引起的应变的大小。磁响应的差异与拉伸应变下优先占据 Mn x(2) - y(2) （面内）d 轨道和压应变下优先占据 3z(2) - r(2) （面外）轨道有关，导致 LSMO 层内竞争性铁磁和反铁磁交换相互作用。这些结果强调了轨道、结构和自旋自由度的相对贡献及其在原子薄晶体复合氧化物层中的可调性。
We investigate the effect of strain and film thickness on the orbital and magnetic properties of LaSrCrO3 (LSCO)/LaSrMnO3 (LSMO) heterostructures using bulk magnetometry, soft x-ray magnetic spectroscopy, first-principles density-functional theory, high-resolution electron microscopy, and x-ray diffraction. We observe an antiparallel ordering of the magnetic moments between the ferromagnetic LSMO layers and the LSCO spacers, leading to a strain-independent ferromagnetic ground state of the LSCO/LSMO heterostructures for LSMO layers as thin as two unit cells. As the LSMO thickness is increased, a net ferromagnetic state is maintained, however, the average magnetic moment per Mn is found to be dependent on the magnitude of the substrate-induced strain. The differences in the magnetic responses are related to preferential occupation of the Mn x(2) - y(2) (in-plane) d orbitals for tensile strain and 3z(2) - r(2) (out-of-plane) orbitals under compressive strain, leading to competing ferromagnetic and antiferromagnetic exchange interactions within the LSMO layers. These results underscore the relative contributions of orbital, structural, and spin degrees of freedom and their tunability in atomically thin crystalline complex oxide layers.