Origin of enhanced anisotropy in FePt-C granular films revealed by XMCD

Authors

Robert Streubel, Lawrence Berkeley National LaboratoryFollow
Alpha T. N'Diaye, Lawrence Berkeley National Laboratory
Kumar Srinivasan, Western Digital
Antony Ajan, Western Digital
Peter Fischer, Lawrence Berkeley National LaboratoryFollow

Date of this Version

4-22-2019

Document Type

Article

Citation

Appl. Phys. Lett. 114, 162401 (2019);

doi: 10.1063/1.5092719

Comments

Published under license by AIP Publishing. Used by permission.

Abstract

We study the effect of carbon segregants on the spin and orbital moments of L10 FePt granular media using x-ray magnetic circular dichroism (XMCD) spectroscopy and report an effective decoupling of the structural film properties from the magnetic parameters of the grains. The carbon concentration reduces the grain size from (200 ± 160) nm2 down to (50 ± 20) nm2 for 40 mol. %C and improves sphericity and the order of grains, while preserving the crystalline order, spin and orbital moments, and perpendicular magnetocrystalline anisotropy. We identify the primary cause of enhanced saturation and coercive fields as the reduced demagnetization fields of individual grains. The ability to shrink grains without impairing their magnetic properties is a critical requirement for the commercialization of Heat-Assisted Magnetic Recording.