Correlations Between X-Ray Microstructures and Magnetic Properties of CoCrTa Alloy thin Films

Abstract

AbstractThin film structures determined by X-ray reflection and transmission diffractometer methods has been used to co rrelate with th e magnetic p roperties of CoCrTa thin films. Well-crystallized CoCrTa alloy particles with strong h.c.p. c-axis preferred oriented normal to the film surfaces were found to be mainly responsible for the perpendicular magnetic anisotropy observed in specimens IL and 8L, whereas poorly crystallized CoCrTa particles in the 150Å thick magnetic layers of a third specimen 33L have led to an observed longitudinal magnetization. Microstrains generated by the crystalline - amorphous interface stresses induced an enhanced perpendicular magnetic anisotropy in specimen 8L. Values of crystallite size D determined from the Warren-Averbach analysis were correlated with the coercivities He. Analysis of the He vs. D curve indicated th a t the critical particle size for a magnetic multi- to single-domain transition was 270± 25Å. The retention in coercivity (Hc=175 Oe) at a small particle size (D=75Å) in specimen 8L suggested that strong interparticle interactions existed among the wellcrystallized CoCrTa particles. A much smaller retention in coercivity (Hc=90 Oe) at D=70Å of specimen 33L indicated the inter particle interactions in poorly crystallized CoCrTa layers were relatively weak.