Veis M, Zahradnik M, Antos R, Visnovsky S, Lecoeur Ph, Esteve D, Autier-Laurent S, Renard J-P, Beauvillain P
Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116, Prague 2, Czech Republic.
d'Electronique Fondamentale, IEF/UMR 862, Université Paris Sud XI, F-91405 Orsay Cedex, France.
Sci Technol Adv Mater. 2013 Dec 3;15(1):015001. doi: 10.1088/1468-6996/15/1/015001. eCollection 2014 Feb.
Pulse laser deposited LaSrMnO ultrathin films on SrTiO substrates were characterized by polar and longitudinal Kerr magneto-optical spectroscopy. Experimental data were confronted with theoretical simulations based on the transfer matrix formalism. An excellent agreement was achieved for a 10.7 nm thick film, while a distinction in the Kerr effect amplitudes was obtained for a 5 nm thick film. This demonstrated the suppression of ferromagnetism due to the layer/substrate interface effects. A revised, depth-sensitive theoretical model with monolayer resolution described the experimental data well, and provided clear cross-section information about the evolution of ferromagnetism inside the film. It was found that the full restoration of the double-exchange mechanism, responsible for the ferromagnetic ordering in LaSrMnO, occurs within the first nine monolayers of the film. Moreover, all the studied films exhibited magneto-optical properties similar to bulk crystals and thick films. This confirmed a fully developed perovskite structure down to 5 nm.
通过偏振和纵向克尔磁光光谱对脉冲激光沉积在SrTiO衬底上的LaSrMnO超薄膜进行了表征。实验数据与基于转移矩阵形式的理论模拟进行了对比。对于10.7 nm厚的薄膜，二者取得了极好的一致性，而对于5 nm厚的薄膜，克尔效应振幅存在差异。这表明由于层/衬底界面效应导致铁磁性受到抑制。一个经过修正的、具有单层分辨率的深度敏感理论模型很好地描述了实验数据，并提供了关于薄膜内部铁磁性演化的清晰截面信息。研究发现，负责LaSrMnO中铁磁有序的双交换机制在薄膜的前九个单层内完全恢复。此外，所有研究的薄膜都表现出与块状晶体和厚膜相似的磁光特性。这证实了在低至5 nm时钙钛矿结构已完全形成。
