Yun Chao, Li Weiwei, Gao Xingyao, Dou Hongyi, Maity Tuhin, Sun Xing, Wu Rui, Peng Yuxuan, Yang Jinbo, Wang Haiyan, MacManus-Driscoll Judith L
Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom.
State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
ACS Appl Mater Interfaces. 2021 Feb 24;13(7):8863-8870. doi: 10.1021/acsami.1c00607. Epub 2021 Feb 15.
In this work, heteroepitaxial vertically aligned nanocomposite (VAN) LaBaMnO (LBMO)-CeO films are engineered to produce ferromagnetic insulating (FMI) films. From combined X-ray photoelectron spectroscopy, X-ray diffraction, and electron microscopy, the elimination of the insulator-metal (I-M) transition is shown to result from the creation of very small lateral coherence lengths (with the corresponding lateral size ∼ 3 nm (∼7 u.c.)) in the LBMO matrix, achieved by engineering a high density of CeO nanocolumns in the matrix. The small lateral coherence length leads to a shift in the valence band maximum and reduction of the double exchange (DE) coupling. There is no "dead layer" effect at the smallest achieved lateral coherence length of ∼3 nm. The FMI behavior obtained by lateral dimensional tuning is independent of substrate interactions, thus intrinsic to the film itself and hence not related to film thickness. The unique properties of VAN films give the possibility for multilayer spintronic devices that can be made without interface degradation effects between the layers.
在这项工作中，异质外延垂直排列的纳米复合材料（VAN）LaBaMnO（LBMO）-CeO薄膜被设计用于制备铁磁绝缘（FMI）薄膜。通过结合X射线光电子能谱、X射线衍射和电子显微镜分析表明，绝缘体-金属（I-M）转变的消除是由于在LBMO基体中通过设计高密度的CeO纳米柱，形成了非常小的横向相干长度（相应的横向尺寸约为3 nm（约7个晶胞））。小的横向相干长度导致价带最大值的移动和双交换（DE）耦合的降低。在约3 nm的最小横向相干长度下不存在“死层”效应。通过横向尺寸调整获得的FMI行为与衬底相互作用无关，因此是薄膜本身固有的，与薄膜厚度无关。VAN薄膜的独特性能为多层自旋电子器件提供了可能性，这种器件可以在层间无界面退化效应的情况下制造。
