Instability of an Isolated Straight Magnetic Domain Wall

Abstract

An isolated straight magnetic domain wall along the y axis results when a thin slab of magnetic material in the xy plane is exposed to a nonuniform z axis magnetic field of the form H_z=βx, if β is sufficiently large. The behavior of this magnetic system as β decreases is discussed. A magnetic energy calculation shows that sinusoidal deviations from the straight wall become energetically favorable at a critical value β_c. The wavelength of this distortion at β_c and β_c are both expressed in terms of magnetic material properties. Experimental observations of this instability in YbFeO₃ are given, and the magnetic parameters determined this way are in reasonable agreement with those obtained by using other methods. Effects of material inhomogeneieties are discussed, and the transition from the initially distorted straight wall to the demagnetized state of stripe domains is shown.