Magnetic properties and underlayer thickness in SmCo/Cr films

SmCo films with a Cr underlayer have been investigated as potentially attra ctive candidates for high density recording media. Magnetron sputtering was used here to produce Cr/SmCox/Cr films on Si (100) substrates. The magneti c films were deposited at a substrate temperature of 350 degrees C and an A r pressure of 5 mTorr. Cr underlayers were deposited both at 25 degrees C a nd at 350 degrees C and exhibited different textures. Layer thicknesses wer e evaluated using Rutherford backscattering spectroscopy, while SmCo grain size and underlayer texture were determined from a Rietveld analysis of x-r ay diffraction data. The magnetic properties were measured with a vibrating sample magnetometer. The resulting films had in-plane coercivities in the range 4-8 kOe. For a SmCo layer with a thickness of 200 nm, the Cr underlay er thickness was varied in the range 75-300 nm to study its effect on inter granular coupling in the films. For thermally demagnetized samples, both ma gnetizing and demagnetizing remanence curves were measured and used to eval uate switching field distributions and delta m plots. The underlayer textur e was found to affect magnetic properties more strongly than underlayer thi ckness. (C) 2000 American Institute of Physics. [S0021-8979(00)84808-2].