Frequency-domain magnetic resonance spectroscopy of molecular magnetic materials

A brief review is presented of a novel method of high-frequency magnetic resonance spectroscopy, which sweeps the frequency at a fixed magnetic field, including zero field. We describe the main features of this frequency-domain spectrometer which works in the spectral range from 30 GHz to 1.5 THz and at magnetic fields up to 8 T; the temperature can be as low as 0.4 K. The versatility of this technique is demonstrated by means of a number of examples from the field of molecular magnetism.