Shao Y C, Deshpande N G, Chin Y Y, Hsieh S H, Du C H, Wang H T, Chiou J W, Tsai H M, Lin H J, Cheng S L, Lin J G, Asokan K, Yeh P H, Pong W F
Department of Physics, Tamkang University, Tamsui, 251, Taiwan.
q-SpinTech & Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur, 416004, M.S., India.
Sci Rep. 2019 Mar 26;9(1):5160. doi: 10.1038/s41598-019-41433-5.
This study probes the temperature-dependent strain that is strongly correlated with the orbital and magnetic structures of epitaxial films of NdSrMnO (NSMO) that are fabricated by pulsed laser deposition with two thicknesses, 17 (NS17) and 103 nm (NS103) on SrTiO (STO) substrate. This investigation is probed using X-ray diffraction (XRD) and absorption-based techniques, X-ray linear dichroism (XLD) and the X-ray magnetic circular dichroism (XMCD). XRD indicates a significant shift in the (004) peak position that is associated with larger strain in NS17 relative to that of NS103 at both 30 and 300 K. Experimental and atomic multiplet simulated temperature-dependent Mn L-edge XLD results reveal that the stronger strain in a thinner NS17 film causes less splitting of Mn 3d e state at low temperature, indicating an enhancement of orbital fluctuations in the band above the Fermi level. This greater Mn 3d orbital fluctuation can be the cause of both the enhanced ferromagnetism (FM) as a result of spin moments and the reduced Néel temperature of C-type antiferromagnetism (AFM) in NS17, leading to the FM coupling of the canted-antiferromagnetism (FM-cAFM) state in NSMO/STO epitaxial films at low temperature (T = 30 K). These findings are also confirmed by Mn L-edge XMCD measurements.
本研究探究了与通过脉冲激光沉积在SrTiO（STO）衬底上制备的两种厚度（17nm（NS17）和103nm（NS103））的NdSrMnO（NSMO）外延薄膜的轨道和磁结构密切相关的温度依赖应变。本研究采用X射线衍射（XRD）以及基于吸收的技术、X射线线性二色性（XLD）和X射线磁圆二色性（XMCD）进行探测。XRD表明，在30K和300K时，（004）峰位置发生了显著偏移，这与NS17相对于NS103更大的应变有关。实验和原子多重态模拟的温度依赖Mn L边XLD结果表明，较薄的NS17薄膜中较强的应变在低温下导致Mn 3d e态的分裂减少，这表明费米能级以上能带中的轨道涨落增强。这种更大的Mn 3d轨道涨落可能是NS17中由于自旋矩导致的铁磁性（FM）增强以及C型反铁磁性（AFM）的奈尔温度降低的原因，从而导致低温（T = 30K）下NSMO/STO外延薄膜中倾斜反铁磁性（FM-cAFM）态的FM耦合。Mn L边XMCD测量也证实了这些发现。
