Enhancement in Magnetic Anisotropy for hcp-Structured Co Alloy Thin Films Through Pt Addition

The addition effects of Pt in the (0002) Ru underlayer were studied. It was found that the lattice parameter can be tuned as desired through Pt addition in a (0002)-oriented Ru layer. The out-of-plane and in-plane lattice parameter of the RuPt can be increased by 2.3% and 0.44%, respectively. No phase segregation was apparently observed in RuPt films under these process conditions even with a very high Pt content (39%). The RuPt layer thus provides a good template layer to study the Pt addition effects in (0002)-textured hcp Co alloy perpendicular media with a very wide range of Pt content. CoCrPt–SiO <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_2$</tex> films were deposited with a Pt addition level varying from 15% to 40% on an optimally designed RuPt underlayer. The magnetic results showed that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$ H_ k, H_ c, K_ u$</tex> reached a plateau at about 19%–23% Pt content. The maximum values for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$ H_ k, H_ c$</tex> , and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$ K_ u$</tex> are 16.0 kOe, 6.6 kOe, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3.1 times 10^6$</tex> erg/cm <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$^3$</tex> , respectively.