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arXiv · 1407.3160

A 4-fold-symmetry hexagonal ruthenium for magnetic heterostructures exhibiting enhanced perpendicular magnetic anisotropy and tunnel magnetoresistance

Zhenchao Wen·Hiroaki Sukegawa·Takao Furubayashi·Jungwoo Koo·Koichiro Inomata·Seiji Mitani·Jason Paul Hadorn·Tadakatsu Ohkubo·Kazuhiro Hono
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Abstract

An unusual crystallographic orientation of hexagonal Ru with a 4-fold symmetry emerging in epitaxial MgO/Ru/Co2FeAl/MgO heterostructures is reported, in which an approximately Ru(02-23) growth attributes to the lattice matching among MgO, Ru, and Co2FeAl. Perpendicular magnetic anisotropy of the Co2FeAl/MgO interface is substantially enhanced as compared with those with a Cr(001) layer. The MTJs incorporating this structure gave rise to the largest tunnel magnetoresistance for perpendicular MTJs using low damping Heusler alloys. The 4-fold-symmetry hexagonal Ru arises from an epitaxial growth with an unprecedentedly high crystal index, opening a unique pathway for the development of perpendicular anisotropy films of cubic and tetragonal ferromagnetic alloys.

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Zhenchao Wen, Hiroaki Sukegawa, Takao Furubayashi, Jungwoo Koo, Koichiro Inomata, Seiji Mitani, Jason Paul Hadorn, Tadakatsu Ohkubo, Kazuhiro Hono. 2014-08-16. A 4-fold-symmetry hexagonal ruthenium for magnetic heterostructures exhibiting enhanced perpendicular magnetic anisotropy and tunnel magnetoresistance. https://doi.org/10.1002/adma.201401959

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