Scanning thermal microwave resonance microscopy

Local detection of ferromagnetic resonance in magnetically ordered materials is achieved by local thermal modulation of the microwave resonance absorption with a scanning thermal microscope. A scanning thermal microwave resonance microscope was constructed based on a microwave bridge with an X-band cavity and a thermal nano-probe contacted to the sample at the wall of the cavity. The technique has been tested on an epitaxial iron film which exhibited lateral inhomogeneities due to a partial oxidation of iron. Different types of oxidation could be distinguished. The locally resolved ferromagnetic resonance spectra are compared with the result of an integral measurement using conventional detection techniques of the ferromagnetic resonance with the same set-up. The lateral resolution achievable with the thermally modulated ferromagnetic resonance measurements was about 200 nm for the investigated iron film.