Classical and quantum mechanical theories of microwave heating of magnetic materials

We present our theoretical studies of the heating of magnetic particles of metals and their oxides by a microwave magnetic field. The Heisenberg model is used for classical spins of metal oxides, and quantum mechanical (ab initio) method is adopted for the origin of magnetization and its response to microwaves for both metals and metal oxides. We quantitatively pin down the heating mechanism of magnetite and titanium oxides (the latter only for the case with oxygen defects) in terms of 3d electron spins [Phys.Rev.B, 2009]. We also show our progress in ab initio calculations of metal iron and magnetite, which yields the information of their magnetic properties and response to microwaves.