Magnetic dead layers in sputtered Co40Fe40B20 films

The magnetic moment of Co(40)Fe(40)B(20) electrodes has been investigated as a function of thickness for films prepared by magnetron sputtering on Si/SiO(2)/MgO and Si/SiO(2) substrates. On MgO, the metal film becomes discontinuous and superparamagnetic with no stable ferromagnetic moment below 1.0 nm, whereas on Si/SiO(2), there appears to be a 0.7 nm dead region for all film thicknesses. The dead layer is attributed to an interdiffusion region at the interface with the substrate where there are weakly coupled noncollinear spins and a 0.2 nm dead layer associated with the Ta cap. The discontinuous ferromagnetic films maybe useful for the wide-range linear field sensors. (c) 2008 American Institute of Physics.