Magnetic amplifying magneto-optical systems: Physics and applications.

摘要

This thesis describes the theoretical and experimental investigation of magnetic amplifying magneto optical systems (MAMMOS) along with the conception of two applications based on MAMMOS. The work has six major accomplishments. First, a simplified model of MAMMOS was created. The model determines if bits are read by testing the nucleation condition in the readout layer. The model's output provides insight into the operation of MAMMOS and was used in the performance analysis of various MAMMOS recording schemes.; Second, the expansion of domains in the readout layer was modeled. In the model, domain wall forces are calculated and used to move the wall until a stable condition is found in the system. The expansion and MAMMOS models were integrated to create a complete system model. Using this model, the size and shape of domains expanded in MAMMOS can be investigated.; Third, the domain expansion speed in the MAMMOS readout layer was experimentally investigated. The read back signal was measured in a working MAMMOS system using an ultra-fast monolithic photodetector/amplifier chip. The measured expansion and collapse occurred in less than 2 and approximately 5 ns respectively, indicating the limiting factor to MAMMOS speeds may be the collapse process.; Fourth, a new method of encoding and reading information in MAMMOS using the position of domains was introduced and theoretically investigated. The new domain position detection (DPD)-MAMMOS technique provides several advantages including a lower clock frequency, larger power margins, and integrated clock recovery. Using the model, DPD-MAMMOS was shown to outperform other systems for position noise levels less than 30 nm.; Fifth, a new read only memory (ROM) structure that is compatible with and has the density advantages of MAMMOS was introduced and investigated. This MAMMOS-ROM is a low-cost, single-layer ROM which is similar to a compact disc (CD) in production.; Sixth, a new technique was introduced for measuring nucleation coercivity distributions in magneto-optic (MO) films using a vibrating sample magnetometer (VSM). Using this technique, it was determined that the small area nucleation coercivity of the MAMMOS readout layer is greater than its bulk coercivity by a factor of 10 or more.