Temperature dependent chemical ordering in FePt(001) and FePt(110) films

The growth temperature is one of the critical parameters in the formation of the chemically ordered L1(0) phase in FePt. To uniquely determine the influence of growth temperature, while other growth parameters remain fixed, we present the "temperature wedge method" where a calibrated temperature gradient of several hundred Kelvin is established across the substrate during co-deposition of Fe and Pt. Samples were deposited in a temperature range of 250 degrees C-600 degrees C simultaneously on MgO(001) and MgO(110) substrates. The Feapproximate to 50Ptapproximate to 50 composition was verified by Rutherford backscattering. The chemical order parameter, S, at different positions along the samples, i.e., at different growth temperatures, was determined by x-ray diffraction measurements, and it was found that at all temperatures S(001)> S(110). Perpendicular and in-plane magneto-optic Kerr hysteresis loop measurements indicate large magnetic anisotropy at the "hot ends" of the samples, corresponding to large values of S. (C) 2000 American Institute of Physics. [S0021-8979(00)61108-8].