School of Chemistry and Materials Science, Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University , Linfen 041004, China.
Research Institute of Materials Science, Shanxi Normal University , Linfen 041004, China.
ACS Appl Mater Interfaces. 2017 Jan 25;9(3):3156-3160. doi: 10.1021/acsami.6b14372. Epub 2017 Jan 13.
Artificial heterostructures based on LaNiO (LNO) have been widely investigated with the aim to realize the insulating antiferromagnetic state of LNO. In this work, we grew [(LaSrMnO)-(LaNiO)] superlattices on (001)-oriented SrTiO substrates by pulsed laser deposition and observed an unexpected exchange bias effect in field-cooled hysteresis loops. Through X-ray absorption spectroscopy and magnetic circular dichroism experiments, we found that the charge transfer at the interfacial Mn and Ni ions can induce a localized magnetic moment. A remarkable increase of exchange bias field and a transition from metal to insulator were simultaneously observed upon decreasing the thickness of the LNO layer, indicating the antiferromagnetic insulator state in 2 unit cells LNO ultrathin layers. The robust exchange bias of 745 Oe in the superlattice is caused by an interfacial localized magnetic moment and an antiferromagnetic state in the ultrathin LNO layer, pinning the ferromagnetic LaSrMnO layers together. Our results demonstrate that artificial interface engineering is a useful method to realize novel magnetic and transport properties.
基于 LaNiO（LNO）的人工异质结构已经被广泛研究，旨在实现 LNO 的绝缘反铁磁态。在这项工作中，我们通过脉冲激光沉积在（001）取向的 SrTiO 衬底上生长了[(LaSrMnO)-(LaNiO)]超晶格，并在磁场冷却的磁滞回线中观察到了意外的交换偏置效应。通过 X 射线吸收光谱和磁圆二色性实验，我们发现界面 Mn 和 Ni 离子的电荷转移可以诱导局域磁矩。随着 LNO 层厚度的减小，观察到交换偏置场的显著增加和金属到绝缘体的转变，这表明在 2 个单位细胞 LNO 超薄层中存在反铁磁绝缘态。超晶格中 745 Oe 的强交换偏置是由界面局域磁矩和超薄 LNO 层中的反铁磁态引起的，这将铁磁 LaSrMnO 层固定在一起。我们的结果表明，人工界面工程是实现新型磁和输运性质的一种有用方法。
