STRUCTURE AND MAGNETIC-PROPERTIES OF FE-CR-N SPUTTER-DEPOSITED FILMS

Structure and magnetic properties of Fe-Cr-N ternary films prepared by DC magnetron facing-target sputtering have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission e lectron microscopy (TEM), vibrating sample magnetometry (VSM) and Moss bauer effect. These films exhibit perpendicular magnetic anisotropy. W e found that N-2-to-Ar flow ratio, Fe-Cr target area ratio and substra te temperature during film preparation are the factors influencing the anisotropy. Adjusting the chemical composition and deposition paramet ers, we obtained saturation magnetization of 300-400 emu/cm(3) acid pe rpendicular coercivity of 800-1100 Oe. XRD measurements show that the films generally consist of the alpha-Fe(Cr) and gamma'-(Fe,Cr)(4)N-x(x < 1) phases, and that the enhancement of perpendicular anisotropy is always accompanied by a decrease in the grain size of alpha-Fe(Cr) pha se and growth of the gamma'-(Fe,Cr)(4)N-x phase with a pronounced (200 ) texture. The Mossbauer spectra show that the gamma'-(Fe,Cr)(4)N-x ph ase is nonmagnetic at room temperature. Using the SEM and TEM, we foun d that the nonmagnetic gamma'-(Fe,Cr)(4)N-x phase displays columnar gr owth and that the small ferromagnetic alpha-Fe(Cr) grains of about 2-2 0 nm in diameter are located at grain boundaries of gamma'-(Fe,Cr)(4)N -x grains. Shape anisotropy seems to play an important part in the per pendicular magnetic anisotropy in these Fe-Cr-N films.