Surface acoustic wave modulator using single crystal films of lithium ferrite

Abstract

A surface acoustic wave (SAW) device formed by an unitary insulating, magostrictive ferrite, slab whose easy axis of magnetization is initially (prior to the application of a d.c. magnetic biasing field) perpendicular to the direction of SAW-wave propagation. For example, the easy axis of magnetization in a single-crystal lithium ferrite slab is the <111> axis. Therfore this axis is aligned perpendicular to the SAW wave propagation direction and parallel to the edges of the SAW device. Application of a dc magnetic field swings the magnetic moments such that they will be parallel with the SAW wave propagation. Materials useful in carrying out this invention are those which have (1) an easy axis of magnetization, (2) good insulator qualities and (3) the magnetostrictive property. A dc magnetic field is applied parallel with the SAW direction or perpendicular to the easy axis of the material in order to align the magnetic moments in the direction of the SAW wave propagation. Such alignment of the magnetic moments of the material causes a delay in propagation time of the SAW wave.

Dependencies are inferred from the claim text.