Micromechanical detection of magnetic resonance by angular momentum absorption

Observations of electron paramagnetic resonance by means of the angular momentum absorbed by a small sample are reported. The method is based on the detection of the torque induced in a microcantilever, like the ones employed in atomic force microscopy, integral with the sample. The results obtained with this experimental scheme are compared with the ones of the Sidles–Rugar method exploiting a force detection of the magnetic resonance in presence of strong magnetic field gradients. In particular, the signal drawn by angular momentum absorption shows opposite trends when the static magnetic field is swept in opposite directions, contrary to the case of experiments performed with force detection. The shape of the signal is characterized at different values of the static field and of radiation intensity.