Magnetic and magnetoresonant properties of thin-film Fe/Ag/Co/CoO heterostructure synthesized by combined molecular beam epitaxy and reactive magnetron sputtering

Abstract

In the paper, we report on growth conditions, structure characterization, magnetic and magnetoresonance studies of thin-film Fe/Ag/Co/CoO heterostructure deposited ontop of the single-crystal (001)-MgO substrate utilizing in situ combination of molecular beam epitaxy and magnetron sputtering. The molecular beam deposition was applied to grow the first, iron layer epitaxially on MgO realizing the 45-degree lattice matching between the magnesium oxide and the body-centered cubic iron. Subsequent silver layer was also grown epitaxially with the favorable 45-degree lattice matching between the iron and silver. Next, Co-metal and the top, cobalt oxide, layers were deposited by magnetron sputtering and reactive sputtering, respectively, after moving the sample into a magnetron sputtering chamber without breaking the ultra-high vacuum conditions. Magnetometry and ferromagnetic resonance studies of the resulting heterostructure have revealed a combination of the four-fold and uniaxial anisotropies in the film plane at temperatures well above the Neel temperature for antiferromagnetic CoO (T_N = 291 K). After field-cooling of the sample down to T = 180 K, ferromagnetic resonance measurements following the major magnetic hysteresis loop have shown a correlated precession of the iron and cobalt layers magnetizations giving the evidence of the interlayer coupling through the silver interlayer.