Dislocation Control of Magnetization

Abstract

The stress fields of edge and screw dislocations are analyzed to determine whether dislocations can exert independent magnetostrictive control over magnetization in magnetite. The stress-defined easy direction near a screw dislocation is described by a 45° helix or spiral about the dislocation line, although exchange and anisotropy energy suppress the spiral angle to less than 30°. The stress-defined easy directions near an edge dislocation are primarily normal to the dislocation line with a small region favoring magnetization parallel to the line. Single edge or screw dislocations can not control magnetization independent from the surrounding domain, even in the absence of a demagnetizing field, although both types will certainly produce local deflections of the spins within a domain.