Asymmetric modification of the magnetic proximity effect in Pt/Co/Pt trilayers by the insertion of a Ta buffer layer

Abstract

The magnetic proximity effect in top and bottom Pt layers induced by Co in Ta/Pt/Co/Pt multilayers has been studied by interface sensitive, element specific x-ray resonant magnetic reflectivity. The asymmetry ratio for circularly polarized x-rays of left and right helicity has been measured at the Pt L3 absorption edge (11567 eV) with an in-plane magnetic field (±158 mT) to verify its magnetic origin. The proximity-induced magnetic moment in the bottom Pt layer decreases with the thickness of the Ta buffer layer. Grazing incidence x-ray diffraction has been carried out to show that the Ta buffer layer induces the growth of Pt(011) rather than Pt(111) which in turn reduces the induced moment. A detailed density functional theory study shows that an adjacent Co layer induces more magnetic moment in Pt(111) than in Pt(011). The manipulation of the magnetism in Pt by the insertion of a Ta buffer layer provides a new way of controlling the magnetic proximity effect which is of huge importance in spin-transport experiments across similar kind of interfaces.

Impact of the magnetic proximity effect in Pt on the total magnetic moment of Pt/Co/Ta trilayers studied by x-ray resonant magnetic reflectivity

“…The difference in the induced moments among the trilayers might arise due to differently textured crystal growth for Pt grown on Co compared to Pt grown on the substrate Si/SiO 2 . For example, it was recently shown that different textures of Pt thin films result in a different magnitude of the MPE 35 . The extracted thicknesses of the Pt spin-polarized layer are 0.9 nm and 0.8 nm for Ta/Co/Pt and Pt/Co/Ta respectively.…”

“…Moreover, it was shown by XRMR that the MPE is independent from the Pt a) Electronic mail: amoskaltsova@physik.uni-bielefeld.de thickness 31 and FM thickness, as well 32 . In addition, the strength of the MPE increases linearly with the FM moment 33,34 and can be manipulated by the use of a Ta buffer layer 35 .…”

Advanced data analysis procedure for hard x-ray resonant magnetic reflectivity discussed for Pt thin film samples of various complexity

“…First of all, we study a Pt/Fe//MgO bilayer system to illustrate the basic principles of the XRMR analysis describing the MPE in Pt and highlight the pros and cons of the different modeling modes. The detailed analysis of a second system, in which Pt is an integral part of a complex multilayer made of a single Pt layer adjacent to a Co layer that induces MPE, is discussed in appendix C [30,31]. The third example is a PtMnSb thin film, a half-metallic Heusler compound, which is an interesting candidate for studies of intrinsic spin-orbit torques [32], with and without a single Pt layer on top.…”

Quantitative comparison of the magnetic proximity effect in Pt detected by XRMR and XMCD

“…due to different growth conditions) or samples with more than one interface of interest (e.g. trilayers with asymmetric MPE 44,45 ), any XMCD result alone for instance can only reveal changes in the overall averaged magnetic moment value and not the differences in the magnetic moment distribution. Exactly the former case has been highlighted in our presented study.…”