Tunneling spin polarization of Ni clusters embedded in rare gas matrices

Abstract The tunneling magnetoresistance (TMR) of granular films made of well-defined Ni clusters (mean diameter ≈ 4.5 nm ) embedded in the rare gas matrices Kr and Xe has been measured as a function of temperature ( 1.7 K ⩽ T ⩽ 30 K ) . The spin polarization P of the tunneling electrons as obtained from TMR( T = 0 ) is P = 20 ( 1 ) % . This value is compared with those obtained from other tunneling experiments.