  Sr2RuO4 is the only known layered perovskite oxide superconductor without
copper; there is strong evidence for an unconventional ("p-wave") pairing
mechanism, and it has recently been shown to possess a cylindrical,
"quasi-two-dimensional" Fermi surface. Using Sr2RuO4 as a test case for the
detection of quantum oscillations with piezoresistive microcantilevers, the
piezolever torque magnetometry technique was successfully implemented on a
dilution refrigerator. It was possible to reproduce the quantum-oscillatory
magnetization data on all three Fermi surface sheets, in a crystal of microgram
mass. Moreover, an absolute estimate of the amplitude of the oscillation is
provided. We also investigated the phenomenon of torque interaction which
distorts the magnetization signal and introduces harmonics and sidebands to the
dHvA spectrum. As the torque interaction effect grows in strength,
overcriticality is shown to lead to discrete magnetization jumps and to a
near-asymptotically damped "sproing" effect.
