Epitaxial growth and patterning of sputtered Fe films on GaAs(001)

Abstract

Fe(001) films, 10–100 nm thick, were epitaxially grown by magnetron sputtering on GaAs(001) and on 100-nm-thick Au(001) buffer layers in an UHV-based sputtering system. Excellent epitaxy is inferred from X-ray diffraction measurements and the magnetic anisotropy of the films. From X-ray φ-scans, the epitaxial relationships Fe[100]‖GaAs[100] and Fe[100]‖Au[110] were determined. Magnetic measurements by vibrating sample (VSM) and alternating gradient magnetometry (AGM) show a distinct fourfold in-plane anisotropy with the anisotropy constant of bulk Fe. Large-area patterning of the films was done by holographic lithography and ion beam etching. Square arrays of dots with periods of 300 nm to 1 μm, dot widths of 50 to 490 nm and different heights were made. Magnetization measurements (VSM, AGM) show a clear change in the magnetic properties of the films dominated by the shape anisotropy of the dots. Again, for some of the samples a fourfold in-plane anisotropy can be observed.