ACTIVATION-ENERGY OF INTERDIFFUSION AND INTERFACE STRUCTURE FOR COFE CU SPIN-VALVES/

Annealing time and temperature dependences of MR ratio in CoFe/Cu spin -valves were investigated. Thermal deterioration of MR ratio was well explained by considering two phenomena with effective activation energ ies of 2.16 eV and 1.57 eV for CoZrNb/NiFe/CoFe/Cu/CoFe/FeMn spin-valv es, and considering one phenomenon with a value of 2.49 eV for CoZrNb/ NiFe/CoFe/Cu/CoPe/IrMn spin-valves, respectively. These values are in good agreement with activation energies of interdiffusion based on the vacancy mechanism. It is shown that no significant change in MR ratio is evaluated from the effective activation energies for the period of more than 10 years at 150 degrees C in CoZrNb/NiFe/CoPe/Cu/CoFe/IrMn spin-valve films.