학술논문
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
Document Type
Article
Source
Current Applied Physics, 14(10), pp.1389-1395 Oct, 2014
Subject
Language
English
ISSN
1567-1739
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 asdeposited DBMTJs and those annealed in a vacuum at 100e350 C for 30 min were then investigated using a complex impedance spectroscopic technique. The ac impedance responses as a function of annealing temperature were further analyzed based on Maxwell's layered dielectric barrier and Maxwell eWagner capacitor models after considering the DBMTJs as having double-capacitor-type structures. The effect of thermal annealing on the ac transport behavior of the DBMTJs was interpreted by examining the equivalent electric circuits fitted to Nyquist plots of each different sample. The effects were found to be due to changes in the structural characteristics in both bulk and interface morphologies of Co and Al2O3 layers. The structural morphology determined the different ac transport modes that occurred in the DBMTJs.