Effect of thermal annealing on the ac impedance of Co(75)/Al2O3(2.3)/Co(5.0)/Al2O3(2.3)/Co(50) double-barrier MTJs

摘要: Abstract Double-barrier magnetic tunnel junctions (DBMTJs) were prepared from Co(75 nm)/Al2O3(2.3 nm)/Co(5 nm)/Al2O3(2.3 nm)/Co(50 nm) sputtering pentalayer films. The ac electrical properties of as-deposited DBMTJs and those annealed in a vacuum at 100–350 °C for 30 min then investigated using complex impedance spectroscopic technique. responses as function annealing temperature further analyzed based on Maxwell's layered dielectric barrier Maxwell–Wagner capacitor models after considering the having double-capacitor-type structures. effect thermal transport behavior was interpreted by examining equivalent electric circuits fitted to Nyquist plots each different sample. effects found be due changes structural characteristics both bulk interface morphologies Co Al2O3 layers. morphology determined modes that occurred DBMTJs.