EXCHANGE-ANISOTROPY OF CRNX FENY/CRNX TRILAYER THIN-FILMS PREPARED BYREACTIVE SPUTTERING/

The exchange magnetic anisotropy of CrNx/FeNy/CrNx trilayer films (x = 1.0 or 1.2, and y = 0.27) has been investigated by means of magnetiza tion measurements. M-H loops of samples composed of nearly-stoichiomet ric CrN1.0 with T-N = 260 K show exchange biasing shift H-eb below 200 K. The uniaxial anisotropy energy per film area is 3.0 x 10(-4) J/m(2 ) at 5 K. For samples with 20 nm-thick FeN0.27 layer and CrN1.0 layers thicker than 20 nm, the values of H-eb at 5 K are almost 13.5 kA/m. T he samples composed of over-stoichiometric CrN1.2 show H-eb below 50 K , indicating that T-N of over-stoichiometric CrN1.2 is much lower than that of nearly-stoichiometric CrN1.0. The values of H-eb for stoichio metric and over-stoichiometric systems are nearly equal below 20 K and , in this temperature range, H-eb shows unusual enhancements with decr easing temperature. It is suggested that the nitrogen composition at t he interface region of stoichiometric CrN layer is over-stoichiometric .