HIGH COERCIVITY IN ULTRATHIN EPITAXIAL MICROMETER-SIZED PARTICLES WITH INPLANE MAGNETIZATION - EXPERIMENT AND NUMERICAL-SIMULATION

Arrays of 2.5x10(7) ultrathin epitaxial W(110)/Fe(110)W(110) submicron particles with in-plane magnetization were fabricated using x-ray lit hography and dry-etching techniques. A large coercive-field increase a s compared to continuous films is observed which is ascribed to the sh ort range of self-demagnetizing fields for ultrathin particles with in -plane magnetization. A method to extract the mean hysteresis loop of a single particle and the coercive field distribution function from me asurements over the whole array is proposed. The analysis is in good a greement with the picture of single-domain particles and of nucleation volumes much smaller than particle dimensions. It is corroborated by micromagnetic calculations performed on isolated ideally square partic les. [S0163-1829(98)07804-7].