We have investigated the magnetorefractive and the magnetic-linear-dichroism effects, which both lead to a frequency-dependent change of the transmission of infrared light, in giant magnetoresistance exchange-biased spin valves. The magnetorefractive effect occurs upon changing the magnetic configuration of the spin valve, whereas the magnetic-linear-dichroism effect occurs when changing the linear polarization direction of the light with respect to the magnetization direction(s) in the spin valve. The systems studied are (Formula presented) with (Formula presented) or NiO. A linear relation between the maximum size of the magnetorefractive effect and the dc magnetoresistance ratio has been found at room temperature. The magnetorefractive effect was analyzed with a simple model containing a frequency-dependent and spin-dependent conductivity that influences the complex refractive index of the spin valve. From the analysis of the measurements, the spin-polarized relaxation times averaged over the layer stack were determined. Extrapolation of the relaxation times to zero Cu thickness yields spin-asymmetry parameters (Formula presented) and (Formula presented) at room temperature for (Formula presented) and NiO-biased spin valves, respectively (Formula presented) and (Formula presented) are the spin-dependent relaxation times). The results indicate that scattering of electrons at the (Formula presented) interface in the spin valves is, at least in part, specular.
|Tijdschrift||Physical Review B - Condensed Matter and Materials Physics|
|Nummer van het tijdschrift||22|
|Status||Gepubliceerd - 1 jan 2000|