R&D: Effects of Annealing on Coercivity, Switching Mechanisms, and Structural Characteristics of Co/Pd Multilayer for Magnetic Memory

Journal of Applied Physics has published an article written by Firdos Ali, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, Alabama 35487, USA, Diego Medina, Eric Fullerton, Department of Electrical and Computer Engineering, University of California San Diego, San Diego, California 92093, USA, Subhadra Gupta, Department of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, Alabama 35487, USA, and P. B. Visscher, Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USA.

Abstract: “This study investigates the effects of annealing on the magnetic and structural properties of Co/Pd multilayers, which are promising candidates for perpendicular magnetic tunnel junctions, critical to magneto-resistive random-access memory (MRAM) applications. Co/Pd multilayers with various bilayer counts (5, 10, 15, and 20) were synthesized via DC magnetron sputtering and subjected to annealing at temperatures ranging from 250 to 450 °C. Magnetic measurements, including standard magnetization-vs-field major hysteresis loops and first-order reversal curve analysis, showed that annealing increased coercivity, reaching a maximum of 5100 Oe at 450 °C for 20 bilayers. Magneto-Optical Kerr Effect imaging confirmed domain-wall motion as the switching mechanism, except in the highest temperature annealed samples, which appear to behave more like independent particles. Structural characterization using x-ray diffraction revealed enhanced crystallinity with annealing, indicating improved atomic ordering. Atomic force microscopy demonstrated increased surface roughness with bilayer count due to increased thickness. These results show that Co/Pd-based multilayers are tolerant of high-temperature processing, as required for CMOS-based MRAM.“