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

Journal Article · Mon Apr 22 00:00:00 EDT 2019 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.5092719· OSTI ID:1574323

Streubel, Robert  ^[1]; N'Diaye, Alpha T.  ^[2]; Srinivasan, Kumar ^[3]; Ajan, Antony ^[3]; Fischer, Peter ^[4]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
3. Western Digital, San Jose, CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Santa Cruz, CA (United States)

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. Here, 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.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231; AC02-05-CH11231
• OSTI ID: 1574323
• Alternate ID(s): OSTI ID: 1508435
• Journal Information: Applied Physics Letters, Vol. 114, Issue 16; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE