Magnetic anisotropy is a prerequisite for hysteresis in ferromagnets&colon; without it, a ferromagnet is superparamagnetic. A ferromagnet, like a paramagnetic substance, has unpaired electrons. Physicists often need the magnetization to calculate the moment of a ferromagnet. The magnetization at any point in a ferromagnet can only change by rotation. The measurement of the magnetization of a magnetic material (like a ferromagnet) is an example. If the ferromagnet is large enough, its magnetization can divide into domains. In an Ising ferromagnet below formula 5 this does not happen. Thus electrons with a larger chemical potential will accumulate at the boundary of the ferromagnet. Furthermore, the resonant absorption of microwave energy causes local heating of the ferromagnet. The added energy term implies a shift in the switching field of the ferromagnet. An electric current passing through a ferromagnet therefore carries both charge and a spin component. Upon cooling, the spins will often enter a ferromagnet (or antiferromagnet) phase. Note that since this is spinning, this is not a non-moving ferromagnet. The subscript F describes the properties of the ferromagnet and AF to the antiferromagnet.