Quantum Condensed Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
Instruments and Source Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
ACS Appl Mater Interfaces. 2017 Jun 7;9(22):19307-19312. doi: 10.1021/acsami.7b03252. Epub 2017 May 25.
Understanding the magnetism at the interface between a ferromagnet and an insulator is essential because the commonly posited magnetic "dead" layer close to an interface can be problematic in magnetic tunnel junctions. Previously, degradation of the magnetic interface was attributed to charge discontinuity across the interface. Here, the interfacial magnetism was investigated using three identically prepared LaSrMnO (LSMO) thin films grown on different oriented SrTiO (STO) substrates by polarized neutron reflectometry. In all cases the magnetization at the LSMO/STO interface is larger than the film bulk. We show that the interfacial magnetization is largest across the LSMO/STO interfaces with (001) and (111) orientations, which have the largest net charge discontinuities across the interfaces. In contrast, the magnetization of LSMO/STO across the (110) interface, the orientation with no net charge discontinuity, is the smallest of the three orientations. We show that a magnetically degraded interface is not intrinsic to LSMO/STO heterostructures. The approach to use different crystallographic orientations provides a means to investigate the influence of charge discontinuity on the interfacial magnetization.
理解铁磁体和绝缘体界面处的磁性至关重要，因为通常假定的接近界面的磁性“死”层在磁性隧道结中可能会出现问题。以前，磁性界面的退化归因于界面处的电荷不连续性。在这里，使用极化中子反射法研究了在不同取向的 SrTiO（STO）衬底上生长的三个相同制备的 LaSrMnO（LSMO）薄膜的界面磁性。在所有情况下，LSMO/STO 界面处的磁化强度都大于薄膜体相。我们表明，在具有（001）和（111）取向的 LSMO/STO 界面处的界面磁化强度最大，它们在界面处具有最大的净电荷不连续性。相比之下，LSMO/STO 在（110）界面处的磁化强度最小，（110）界面没有净电荷不连续性。我们表明，磁性退化的界面不是 LSMO/STO 异质结构的固有特性。使用不同晶体学取向的方法提供了一种研究电荷不连续性对界面磁化强度的影响的手段。
