Magnetization-graded ferromagnets: The magnetic analogs of semiconductor junction elements

Abstract

Compositionally graded ferrites are formed as the magnetic analogs of semiconductor junction devices. The internal, or the “built-in,” magnetic field is intrinsic to the structure and is determined from ferromagnetic resonance microscopy. Magnetic analysis of a nickel–zinc–ferrite system in terms of its spatially dependent order parameter, the magnetization, yields a value for the internal magnetic field consistent with experimental observations. Our results are extended to the general class of ferroic and other “smart” materials via a spatially dependent free-energy potential.