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arXiv · 2308.04149

Fully epitaxial fcc(111) magnetic tunnel junctions with a Co90Fe10/MgAlO/Co90Fe10 structure

Jieyuan Song·Thomas Scheike·Cong He·Zhenchao Wen·Tadakatsu Ohkubo·Kazuhiro Hono·Hiroaki Sukegawa·Seiji Mitani
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Abstract

Magnetic tunnel junctions (MTJs) with bcc(001)-type structures such as Fe(001)/MgO(001)/Fe(001), have been widely used as the core of various spintronic devices such as magnetoresistive memories; however, the limited material selection of (001)-type MTJs hinders the further development of spintronic devices. Here, as an alternative to the (001)-type MTJs, an fcc(111)-type MTJ using a fully epitaxial CoFe/rock-salt MgAlO (MAO)/CoFe is explored to introduce close-packed lattice systems into MTJs. Using an atomically flat Ru(0001) epitaxial buffer layer, fcc(111) epitaxial growth of the CoFe/MAO/CoFe trilayer is achieved. Sharp CoFe(111)/MAO(111) interfaces are confirmed due to the introduction of periodic dislocations by forming a 5:6 in-plane lattice matching structure. The fabricated (111) MTJ exhibits a tunnel magnetoresistance ratio of 37% at room temperature (47% at 10 K). Symmetric differential conductance curves with respect to bias polarity are observed, indicating the achievement of nearly identical upper and lower MAO interface qualities. Despite the charge-uncompensated (111) orientation for a rock-salt-like MAO barrier, the achievement of flat, stable, and spin-polarized barrier interfaces opens a promising avenue for expanding the design of MTJ structures.

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Jieyuan Song, Thomas Scheike, Cong He, Zhenchao Wen, Tadakatsu Ohkubo, Kazuhiro Hono, Hiroaki Sukegawa, Seiji Mitani. 2023-08-08. Fully epitaxial fcc(111) magnetic tunnel junctions with a Co90Fe10/MgAlO/Co90Fe10 structure. https://arxiv.org/abs/2308.04149

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