A study on tunneling magnetoresistance in magnetic tunnel junctions oxidized by ozone

Abstract

Magnetic tunnel junctions of Ta/NiFe/FeMn/NiFe/CoFe/Al2O3/CoFe/NiFe structure were studied. Two different types of oxidation atmosphere were used to form the barrier laver; plasma oxidation and ozone oxidation. The maximum tunneling magneto resistance ratio of 32% was observed at room temperature for 50 min ozone oxidation. The junction resistance was several hundred ohms at 0.1 mm x 0.2 mm junction. This is about one order lower than that of the plasma oxidized junctions. The plasma free oxidation process would eliminate the possible structural damage by an oxygen ion bombardment and give improved control over the tunnel barrier growth. (C) 2001 Published by Elsevier Science B.V.