1 / 2018-03-12 00:36:55

Temperature-dependent interlayer exchange coupling strength in synthetic antiferromagnetic [Pt/Co]4/Ru/[Co/Pt]4 multilayers

层间交换耦合,热稳定性,人工合成反铁磁多层膜

Perpendicularly magnetized tunneling junctions that contain synthetic antiferromagnetic (SAF) structures show promise as reliable building blocks to meet the demands of perpendicular magnetic anisotropy-based spintronic devices. However, the widespread Pt/Co based SAF multilayer with a nonmagnetic Ru spacer is still a challenge due to the structural discontinuity or intermixing that occurs at high temperature. In this work, the thermally robust characteristics of the interlayer exchange coupling (IEC) strength Jex for sputtered SAF [Pt/Co]4/Ru/[Co/Pt]4 multilayer with strong perpendicular anisotropy has been investigated. The magnetization hysteresis (MH) loop of the SAF multilayer was measured using VSM at the temperature range from 100K to 800K. Both the out-of-plane and in-plane MH loops at room temperature were shown in Figure 1(a), which indicates the perpendicular anisotropy property of the SAF multilayer. Sharp spin-flips appear at the exchange coupling filed Hex with a small net moment at low perpendicular field. The temperature-dependence of Hex and Jex were shown in Figure 1(b). It is demonstrated that the Hex and Jex of our SAF multilayer is very sensitive to the temperature variation, which depends not only on the spacer Fermi surface, but also the degree of the confinement of carriers in the quantum well of spacer. As shown in Figure 1(b), the Hex and Jex decrease from 6.17 kOe and -4.49 erg/cm2 to 1.80 kOe and -0.83 erg/cm2, respectively, when the temperature increases from 100K to 700K. It's worth pointing out that our SAF multilayer shows high thermal stability even at 700K (Hex = 1.80 kOe and Jex = -0.83 erg/cm2) in comparison with other reports (i.e. [Pd/Co]/Ru(1.3)/[Co/Pd], Jex = -0.38 erg/cm2 at 673 K, Sci. Rep. 6, 21324, 2016). These experimental results would provide useful information for the design of SAF structures with better magnetic performance and thermal stability.