Mechanism of magnetization enhancement at CoO/permalloy interfaces

Abstract

We investigate the magnetic properties of CoO(111)/permalloy(111) interfaces by ab-initio calculations. We employ a (5 × 5)CoO/(6 × 6)permalloy supercell, to satisfy the ∼5:6 ratio of the lattice constants, and optimize the atomic density near the interface. While experimentally the interface magnetization is 14% higher than in the bulk, we find for the purely O/Co-terminated interface a decrease/increase by 140%/40%, which enables insight into the real interface with partial O deficiency and atomic intermixing. Intermixing between Fe and Ni significantly lowers the total energy, which promotes Fe accumulation at the interface. Since Co-O bonds are energetically favorable, O diffusion into the permalloy is suppressed.

Roughness effects in uncompensated antiferromagnets

“…36 Moreover, extrinsic parameters may influence the spin texture at the interface, such as, e.g., intermixing between AFM and FM, such as in NiO/NiFe multilayers. 37 Such an intermixing can dramatically decrease the performance of the exchange coupling, but it can also enhance the magnetization at the interface, as seen in experiments 38 and ab-initio calculations 39 for the CoO/NiFe system.…”