Measurement of the Domain-Wall Energy of the Orthoferrites

Abstract

A new technique for the direct measurement of the magnetic domain‐wall energy per unit area has been developed and applied in the orthoferrites. A previously reported technique to determine the domain‐wall energy per unit area from the radii of cylindrical domains has been reinterpreted. The simplest possible domain‐wall configuration (a set of planar, parallel, equally spaced domain walls) has been predicted and observed to be stable in properly prepared samples. In the new technique to measure the domain‐wall energy per unit area, these planar walls are controllably stretched into sinusoidal corrugations by an applied magnetic field to increase the total wall area and total wall energy within a sample. The increase of wall area has been observed by the Bitter and Faraday techniques. Calculation of the work exerted by the applied and demagnetizing magnetic fields in forcing the controlled increase of wall area yields the new measure of the domain wall energy per unit area; the domain wall energy per unit area of ErFeO₃ at 25°C has been measured to be 1.95 erg/cm²±5%. The precision is limited by sample inhomogeneity and experimental uncertainty, not by inherent uncertainty in the technique.