1. In an Ising ferromagnet below T _ c this does not happen. 2. Below this temperature the ferromagnet has a spontaneous magnetization. 3. The simplest way of understanding spin waves is to consider the Heisenberg ferromagnet : 4. The magnetization at any point in a ferromagnet can only change by rotation. 5. The added energy term implies a shift in the switching field of the ferromagnet . 6. The subscript F describes the properties of the ferromagnet and AF to the antiferromagnet. 7. Furthermore, the resonant absorption of microwave energy causes local heating of the ferromagnet . 8. Note that since this is spinning, this is not a non-moving ferromagnet . 9. Note that in the classical continuum case and in dimensions Heisenberg ferromagnet equation has the form 10. Where M is the magnetization of the ferromagnet and \ gamma is the gyromagnetic ratio.
