Effect of [111] texture on the perpendicular magnetic anisotropy of Co/Ni multilayers

Abstract

[111]fcc[111]fcc oriented [Co(2 Å)/Ni(7 Å)]20[Co(2Å)/Ni(7Å)]20 multilayers were prepared by molecular beam epitaxy at room temperature on epitaxial Au/Ag buffer layers grown on chemically etched Si(111) surfaces. NH4FNH4F etching of Si(111) leads to a smaller spread in the 〈111〉 orientation of the Au/Ag buffer layers and the Co/Ni multilayers as compared to a similar sample prepared on HF-etched Si(111). This results in a stronger perpendicular magnetic anisotropy as determined from the magnetic hysteresis loops. Cross-sectional transmission electron microscopy studies show that the magnetic multilayer film is not flat but has significant waviness at both top and bottom surfaces. The observed waviness originates in part from the waviness already present on the surface of the Au buffer layer and appears to be further enhanced by the difference in the surface free energies of Au and the magnetic elements. A flatter Au/Ag buffer layer is essential to further improve the [111] texture of the [Co/Ni] multilayers. © 1998 American Institute of Physics.