Electromagnetically-excited acoustic waves in ferromagnetic metals at low temperatures

Quantitative measurements of the electromagnetic excitation of acoustic waves in a thin nickel single-crystal have been carried out under simple well-defined experimental conditions at liquid-helium temperatures which allow the complementary roles of two different mechanisms of electromagnetic-acoustic coupling to be clearly defined at the surface and in the bulk of the metal. It is pointed out that such measurements can be used as a sensitive a.c. probe of the d.c. magnetic fields at the surface and in the bulk of ferromagnetic metals.