Integrated micromechanical cantilever magnetometry of Ga1-xMnxAs

We have developed a technique for fabricating submicron GaAs micromechanical cantilevers into which lithographically patterned samples grown by molecular beam epitaxy or evaporative deposition are integrated. The torque sensitivity of the 100-nm-thick cantilevers makes them ideal for torsional magnetometry of nanometer-scale, anisotropic samples. We present measurements on samples of the ferromagnetic semiconductor Ga1-xMnxAs at temperatures from 350 mK to 65 K and in fields from 0 to 8 T. By measuring the shift in the resonant frequency of the cantilevers, we demonstrate a moment sensitivity of 3 x 10(6) mu(B) at 0.1 T, an improvement of nearly five orders of magnitude upon existing torsional magnetometers. (C) 1999 American Institute of Physics. [S0003-6951(99)03934-0].