Non-contact GMR measurements of synthetic spin valves using infrared reflection spectroscopy

In this paper, the sputtered synthetic spin valve samples studied consisted of a pinned layer of an antiferromagnetically coupled CoFe/Ru/CoFe trilayer in direct contact with a layer of the antiferromagnet PtMn. The pinned layer is separated from the free CoFe/NiFe bilayer by a layer of Cu. Two variations of this structure were studied. A top spin valve (TSV) with the pinned layer at the top of the stack and a bottom spin valve (BSV) with the pinned layer at the bottom of the stack. The samples were magnetically characterized using a VSM and dc magnetotransport measurements were made using a four-point probe in a maximum applied magnetic field of /spl plusmn/9 kOe. IR spectra were acquired between 2.5 and 20 /spl mu/m using a Nicolet Fourier transform IR reflection spectrometer. The optimum MRE was obtained for s polarised light using a KRS-5 grid polariser and for an incidence angle of 65/sup o/ with respect to the surface normal.