CORRELATION BETWEEN STRUCTURE AND MAGNETIC-BEHAVIOR OF FE-P AMORPHOUS-ALLOYS

A series of Fe100-xPx alloys (x=11-22) have been prepared by electrode position. Fully amorphous samples (x=16-22) have been investigated fro m both a magnetic and a structural point of view, in order to clarify the magnetic behavior of such alloys. Magnetization, Mossbauer, and ex tended x-ray-absorption fine structure (EXAFS) measurements (in both t he Fe-K and P-K edges) have been performed. The concentration dependen ce of the saturation magnetization at 0 K, the isomer shift, and the m ean hyperfine field have been obtained using the first two techniques and agree with previously reported data. The structural parameters obt ained by EXAFS spectroscopy indicate no change in the Fe-Fe nearest-ne ighbor arrangement in the Series and only a slight increase in the num ber of P atoms around Fe as the P content increases. We observe a T-2 temperature dependence of magnetization, indicative of itinerant rathe r than localized magnetism. The atomic disorder of the samples is disc ussed in terms of the shape of the hyperfine field distributions and t he structural disorder parameters obtained in the fit of the EXAFS spe ctra, and can be related to the behavior of the spontaneous magnetizat ion. The characteristic behavior of the Curie temperature, whose value remains nearly unchanged over the range of composition studied, can b e explained as a cancellation of volume effects and electron transfer from P to the 3d band of Fe.