Magneto-Optical Spectroscopy of RE/TM Alloys and TM/CO Multilayers

Abstract

ABSTRACTThis paper reviews on magneto-optical spectroscopy of alloys, metallic multilayers and interference enhancement structures for magneto-optic (MO) recording. Mainly rare earth transition metal (RE-TM) alloys and Co/transition metal (Co/X) multilayers will be discussed. The read out performance in MO write/read tests is given by tile reflectivity and Kerr rotation strongly depends on the wavelength. While the magneto-optical transitions in the near infrared (IR:≈820nm) are dominated by tile 3d magnetic transition metals Fe and Co, the properties in the ultraviolet (UV: <400nm) can be dominated by either rare earths like Nd or Pr in RE-TM alloys or by exchange polarized Pt or Pd in Co/X multilayers and their respective alloys.In an attempt to correlate the magneto-optic Kerr effect to electronic properties we have systematically investigated alloys and multilayers with x-ray photoemission (XPS) and polar magneto-optical Kerr spectroscopy (0.5–5.3eV range). It is found that electronic 4f levels in Nd or Pr contribute to the Kerr elffct via Γ→, d transitions in the order of 0.3°. Exchange polarized Pd and Pt in Co/X multilayers give rise to a room temperature Kerr rotation in the same order of magnitude via excitations of the 4d and 5d bands, respectively. These effects clearly depend on film compositions and thickness ratios.,