ARTIFICIALLY ORDERED FE-CU ALLOY SUPERLATTICES ON CU(001) - I - STUDIES ON THE STRUCTURAL AND MAGNETIC-PROPERTIES

Metastable fee Fe-Cu alloys in the L1(0) phase have been prepared by s tacking one monolayer of Fe and one monolayer of Cu alternately, [Fe(1 ML)/Cu(1 ML)](n) (where n less than or equal to 25) onto a Cu(001) su bstrate using pulsed-laser deposition. The observed reflection high-en ergy electron-diffraction oscillations for each Fe and Cu layer and th eir growth mode as studied by scanning tunneling microscopy indicate a nearly layer-by-layer growth. Alloys up to n=22 (22 bilayers) have fc c(001) structure, then change from fee to bcc structure. Magnetic hyst eresis loops measured using the magneto-optical Kerr effect indicate t hat for 1 less than or equal to n less than or equal to 25 the films a re ferromagnetic with the easy axis of magnetization within the plane of the films. For the basic unit of double-layer configuration a Curie temperature of 130 K is estimated. It increases linearly with the num ber of stackings reaching a saturation value of 400 K at five double l ayers and beyond.