Energy barrier and effective thermal reversal volume in columnar grains

摘要: Abstract A method to determine the minimum energy path between two stable states in a magnetic system is used investigate reversal of an irregularly shaped columnar grain. The describes magnetization process initiated by thermal excitations zero applied field or fields below intrinsic switching field. In addition barrier, effective volume V eff calculated as function material exchange interaction, uniaxial crystalline anisotropy, and particle length. barrier paths follow that where with decreasing modes go from uniform rotation end nucleation subsequent expansion vortex excitation. decreases increasing anisotropy. Decreasing length also once becomes less than excitation very simple analytic wall model nicely indicates these trends. Analysis measured for CrO 2 Fe explain inferred volumes particles.