Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA.
SuperSTEM, SciTech Daresbury Campus, Daresbury, WA44AD, UK.
Nat Commun. 2015 Apr 16;6:6735. doi: 10.1038/ncomms7735.
Thin-film oxide heterostructures show great potential for use in spintronic memories, where electronic charge and spin are coupled to transport information. Here we use a La0.7Sr0.3MnO3 (LSMO)/PbZr0.2Ti0.8O3 (PZT) model system to explore how local variations in electronic and magnetic phases mediate this coupling. We present direct, local measurements of valence, ferroelectric polarization and magnetization, from which we map the phases at the LSMO/PZT interface. We combine these experimental results with electronic structure calculations to elucidate the microscopic interactions governing the interfacial response of this system. We observe a magnetic asymmetry at the LSMO/PZT interface that depends on the local PZT polarization and gives rise to gradients in local magnetic moments; this is associated with a metal-insulator transition at the interface, which results in significantly different charge-transfer screening lengths. This study establishes a framework to understand the fundamental asymmetries of magnetoelectric coupling in oxide heterostructures.
薄膜氧化物异质结构在自旋电子存储器中有很大的应用潜力，其中电子电荷和自旋与传输信息相耦合。在这里，我们使用 La0.7Sr0.3MnO3 (LSMO)/PbZr0.2Ti0.8O3 (PZT) 模型系统来探索电子和磁性相的局部变化如何介导这种耦合。我们提供了来自 LSMO/PZT 界面的价态、铁电极化和磁化的直接、局部测量，从中我们绘制了界面处的相图。我们将这些实验结果与电子结构计算相结合，阐明了控制该系统界面响应的微观相互作用。我们观察到 LSMO/PZT 界面处的磁不对称性，该不对称性取决于局部 PZT 极化，并导致局部磁矩的梯度；这与界面处的金属-绝缘体转变有关，这导致了电荷转移屏蔽长度的显著不同。这项研究建立了一个理解氧化物异质结构中磁电耦合基本不对称性的框架。
