Kai Liu
Physics Department, University of California, Davis, CA 95616
报告时间：4月18日（周五）10:00
报告地点：唐仲英楼A213会议室
High magnetic anisotropy L10 FePt is the material of choice for the emerging heat-assisted magnetic recording technology. A key limiting factor has been the high annealing temperature (600-650°C) necessary to transform the as-deposited disordered cubic A1 phase into the ordered tetragonal L10 phase. We have achieved (001) oriented L10 FeCuPt thin films, with magnetic anisotropy up to 3.6×107 erg/cm3, using atomic-scale multilayer sputtering and rapid thermal annealing (RTA) at 400 °C for 10 seconds, which is quite benign compared to earlier studies [1]. The artificial ordering in the multilayer structure and a significant tensile stress exerted by an underlying SiO2 seed layer during RTA facilitate the formation of (001) oriented L10 phase. The A1 to L10 phase transformation has been investigated by x-ray diffraction and the first-order reversal curve (FORC) method [2,3]. The L10 ordering takes place via a nucleation-and-growth mode. Traditional x-ray diffraction is not always reliable in generating a true order parameter, due to non-ideal crystallinity of the A1 phase in some of the samples. A magnetization-based L10 phase fraction is extracted, providing a quantitative measure of the L10 phase homogeneity.
This work has been supported by the NSF (DMR-1008791).
[1]. D. A. Gilbert, L. W. Wang, T. J. Klemmer, J. U. Thiele, C. H. Lai, and Kai Liu, Appl. Phys. Lett., 102, 132406, (2013).
[2]. J. E. Davies, O. Hellwig, E. E. Fullerton, G. Denbeaux, J. B. Kortright, and Kai Liu, Phys. Rev. B, 70, 224434, (2004).
[3]. D. A. Gilbert, G. T. Zimanyi, R. K. Dumas, M. Winklhofer, A. Gomez, N. Eibagi, J. L. Vicent, and Kai Liu, Sci. Rep, 4, 4204 (2014).