Exchange Bias Formation Mechanism in (110)Al2O3/Py/Mn/Ta Nanostructures

I.V. Blinov, T.P. Krinitsina, S.A. Matveev, M.A. Milyaev, V.V. Popov, V.V. Ustinov
Institute of Metal Physics, RU

Keywords: exchange bias, diffusion, nanostructure

Summary:

Magnetic multilayer nanostructures possessing exchange bias are of interest for spintronics as effective magnetic field sensors. The mechanism and conditions of the exchange bias formation in (110) Al2O3/Py(30nm)/Mn(100nm)/ Ta(10nm) nanostructures at thermal-magnetic treatment have been studied. The specimens were obtained by magnetron and electron-beam sputtering on (110) Al2O3 substrate. A covering layer of Ta (10 nm) was sputtered to prevent oxidation. The thermal-magnetic treatment was carried out in the vacuum of 10-6 Torr in a constant magnetic field of 2000 Oe. It is shown that at annealing of the bilayers Mn atoms penetrate into permalloy along crystallite boundaries (volume diffusion is completely suppressed at the temperatures studied), and on the Mn enriched boundaries a coating of the ordered antiferromagnetic phase is formed, surrounding the initial permalloy grains. At further annealing this coating grows into the crystallites bulk.