PIEZOMAGNETIZATION OF SINGLE-DOMAIN GRAINS - A GRAPHICAL APPROACH

The remanent magnetic properties of single-domain grains under uniaxial compression are easily interpreted by a graphical method based on the Néel thermal fluctuation theory, provided the stress σ and the magnetic field H are parallel. The change in remanence resulting from a change in magnetic field, stress, or temperature can be represented by the area swept out by a moving “blocking curve” on a graph of grain volume, v, versus microscopic coercive force, Hc. Applying or removing σ moves the blocking curve parallel to the Hc axis a distance 3λσ/Js. This graphical method is useful for visualizing pressure induced remanence (PRM) and pressure demagnetization. If the grain distribution n(v, He) is known, it is also suitable for quantitative analysis. The theory explains some observed relationships between the intensity of PRM and the order in which σ and H are applied and removed, and predicts that these different types of PRM should have measurably different stabilities against AF, thermal, and pressure demagnetization. © 1969, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.