FIELD-DEPENDENT THERMOELECTRIC-POWER AND THERMAL-CONDUCTIVITY IN MULTILAYERED AND GRANULAR GIANT MAGNETORESISTIVE SYSTEMS

The giant magnetoresistance (GMR) effect in granular and multilayer th in films has been widely investigated because of possible device appli cations. Despite this intensive effort, the underlying mechanisms resp onsible for the effect have not been identified. We present measuremen ts of the thermoelectric power (TEP) and thermal conductivity on a wid e variety of granular and multilayer GMR systems. The strong magnetic field dependences of both the TEP and the thermal conductivity are fou nd to be closely related to the magnetoresistance. The TEP measurement s require that the high density of states in the ferromagnetic materia ls play a major role in the GMR effect. The thermal conductivity measu rements indicate that the scattering mechanisms in granular samples ar e elastic while multilayer samples have a significant inelastic, spin- flip component.