Ferromagnetic resonance detection with a torsion-mode atomic-force microscope

We have developed a ferromagnetic resonance (FMR) instrument based on a tor sion-mode atomic-force microscope (AFM). The instrument measures the torque on a magnetized thin film in a static out-of-plane field perpendicular to the film surface. The magnetic film is deposited onto an AFM microcantileve r. FMR measurements are performed at a fixed microwave frequency of 9.15 GH z with a sweeping in-plane field. At the FMR condition, the change in the a verage in-plane magnetization of the film is at a maximum corresponding to a maximum change in the torque on the AFM cantilever. Our instrument is cap able of measuring fluctuations of in-plane magnetization of 63.3 A/m of NiF e film samples with a total volume of 1.1 x 10(-10) cm(3). Given a signal-t o-noise ratio of 40, we estimate a magnetic moment sensitivity of 1.7 x 10( -16) A/m(2). [S0003-6951(00)04109-7].