Magnetocrystalline Anisotropy of Magnetic Grains in Co80Pt20:Oxide Thin Films Probed by X-ray Magnetic Circular Dichroism

Magnetocrystalline Anisotropy of Magnetic Grains in Co 80 Pt 20 :Oxide Thin Films Probed by X-ray Magnetic Circular Dichroism W. Zhang 1 , S. A. Morton 2 , P. K. J. Wong 1, * , X. F. Hu 1 , E. Arenholz 2 , B. Lu 3 , T. Y. Cheng 1 , Y. B. Xu 1, † , and G. van der Laan 4 Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD, UK Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA Seagate Technology, 47010 Kato Road, Fremont, CA 94538, US Diamond Light Source, Chilton, Didcot OX11 0DE, UK Abstract Using angle-dependent X-ray magnetic circular dichroism we have measured magnetic hysteresis loops at the CoL 2,3 edges of oxide-doped Co 80 Pt 20 thin films. The magnetocrystalline anisotropy energy (MAE) of the Co atoms, which is the main source of the magnetocrystalline anisotropy of the CoPt magnetic grains, has beendetermined directly from these element-specific hysteresis loops. When the oxide volume fraction (OVF) is increased from 16.6% to 20.7%, the Co MAE has been found to decrease from 0.117 meV/atom to 0.076 meV/atom.While a larger OVF helps to achieve a smaller grain size, it reduces the magnetocrystalline anisotropyas demonstrated unambiguously from the direct Co MAE measurements.Our results suggest that thoseCo 80 Pt 20 :oxide films with OVF between 19.1% and20.7%aresuitable candidates for high-density magnetic recording. Present address: MESA+ Institute of Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands. Corresponding author: yx2@ohm.york.ac.uk