Ferromagnetic-induced component in piezoresistance of GaMnAs

We have observed a ferromagnetic-induced piezoresistance component in a micromechanical cantilever integrated with a GaMnAs piezoresistor. The temperature and the magnetic-field dependence of the piezoresistance around the ferromagnetic transition reveal that the piezoresistance is modulated by ferromagnetic ordering. The sign of the ferromagnetic-induced component of the piezoresistance is opposite to that of the conventional piezoresistance, though of comparable magnitude. This ferromagnetic-induced piezoresistance has a delayed response to mechanically induced strain, with an experimentally determined response time of 230 +/- 35 ns. DOI: 10.1103/PhysRevB.87.060410