Gyromagnetic resonance in ferrofluids made from manganese ferrite or magnetite particles: influence of a constant axial magnetic field

We have measured the susceptibility of two ferrofluids in the frequency range 0.1–20 GHz. We confine the liquid under test in a coaxial line cell and we use the reflection/transmission method to obtain χ ∗ . If we add a constant axial magnetic field to the microwave field we evidence an increase of the gyromagnetic resonance phenomenon appearing as a consequence of the artificial increase of anisotropy.