OBSERVATION OF MAGNETIC DOMAIN BEHAVIOR IN COLOSSAL MAGNETORESISTIVE MATERIALS WITH A MAGNETIC FORCE MICROSCOPE

Magnetic domain behavior was imaged in calcium-doped lanthanum mangane se trioxide films. Magnetic domains behave differently at temperatures that are well below and near the Curie temperature T-c. At low temper atures the domains are very stable. As temperature rises toward T-c, d omain-domain interactions become weaker and domains become highly mobi le and subject to merging and splitting, yet the domains are still tra ceable. The contrast (which is a measure of magnetization) and size of domains continuously reduce to zero. The temperature at which the dom ains disappear agrees with the T-c obtained by a macroscopic magnetiza tion measurement. Sample defects such as scratches lend to attract mag netic domains.