Spin Polarization Measurments of Co$_{1-x }$-- Pt$_{x}$ alloys by Point Contact Andreev Reflection Spectroscopy

Recently Kaiser \textit{et al.,}$^{1}$ compared the spin polarization measured by spin resolved tunneling spectroscopy (Tedrow-Meservey) and the magnetic moment of Co$_{1-x }$-- Pt $_{x}$ alloys. We have measured the transport spin polarization, P$_{c}$ and magnetic properties of the same series of samples using Point Contact Andreev Reflection Spectroscopy (PCAR). All films with x varying from 0 to 100{\%} and a thickness of $\sim $1000 {\AA} were grown on Si substrates covered with $\sim $250 {\AA} of SiO$_{2}$ by magnetron sputtering. We will present a correlation between spin polarization and magnetization for this series of magnetic alloys and compare our results with the ones obtained in Ref. [1]. 1. C. Kaiser \textit{et al.}, PRL \textbf{94} 247203 (2005).