Nanostructured Exchange-Coupled Magnets

摘要: In recent years, exchange-coupled magnetic nanostructures have attracted much attention in the areas of permanent magnetism, recording, sensors, soft magnetism and spin-electronics. The reason is that suitable nanostructuring may improve performance an artificial material beyond naturally occurring substances, realizing what known as materials-by-design concept. This chapter focuses on magnets, whose ability to store magnetostatic energy described by product. 20th century, product doubled every twelve present-day record-holder Nd2 Fe14 B has products excess 451 kJ/m3. However, outlook for discovering new ternary phases with magnetizations significantly higher than been poor, approaches are necessary if ever double again. For example, predicted Skomski Coey(1993), adding a high polarization, such Fe65 Co35 (µ0 M s = 2.43 T), oriented hard magnet improves grain size regions sufficiently small. Compared theoretical limit 516 kJ/m3 single-phase Nd2Fe14B, suitably nanostructured Sm2 Fe17 N3/Fe65 composites was be 1090 (Skomski Coey, 1993). Related structures investigated number authors (Al-Omari Sellmyer, 1995; Liu et al., 1998a; Sawitchi 2000; Bowden 2000, 1999; Hadjipanayis, Fullerton al. 1999).