MAGNETIZATION REVERSAL MECHANISMS IN NIFE/CU/NIFE/FEMN SPIN-VALVE STRUCTURES

Transmission electron microscopy is used to provide a detailed description of how magnetization reversals take place in NiFe/Cu/NiFe/FeMn spin-valves. Direct observation is made of how both NiFe layers respond to an applied field. Marked differences from the behavior observed in single Permalloy layers of the same thickness are identified. Complex 360 degrees wall structures frequently form and are studied in some detail. A description of their structure is given and a theory involving the compensation of charges from the biased layer is suggested to explain stability. The work has a direct bearing on the performance of spin-valves as sensors as the way the magnetization changes under the influence of an applied field affects the noise characteristics. (C) 1995 American Institute of Physics.