Anisotropy at nano-grain boundary and effective anisotropy between magnetically soft and hard nano-grains

Abstract An expression of anisotropy at grain boundary suitable for different coupling conditions has been given, based on which the effective anisotropy between soft and hard grains 〈 K sh 〉 has been calculated in nanoscaled magnetic materials. The results showed that 〈 K sh 〉 increases rapidly first, then the increase becomes slow, and 〈 K sh 〉 decreases with increasing D s for the same value of D h . 〈 K sh 〉 decreases with increasing D s for all given D h , and the decrease rate becomes slow with increasing D h . In order to obtain higher effective anisotropy between magnetically soft and hard grains, D h should not be less than 25 nm, and D s should be about 10 nm.