Variation in the properties of the interface in a CoFeB∕MgO∕CoFeB tunnel junction during thermal annealing

Variation in the quality of the interface in a CoFeB∕MgO∕CoFeB tunnel junction during thermal annealing was investigated using x-ray photoemission spectroscopy. The formation of B oxide and the reduction of Fe oxide at the bottom interface after thermal annealing near Ta=300°C were found to enhance...

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Veröffentlicht in:Applied physics letters 2007-09, Vol.91 (10)
Hauptverfasser: Jang, Youngman, Nam, Chunghee, Lee, Ki-Su, Cho, B. K., Cho, Y. J., Kim, Kwang-Seok, Kim, K. W.
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Sprache:eng
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Zusammenfassung:Variation in the quality of the interface in a CoFeB∕MgO∕CoFeB tunnel junction during thermal annealing was investigated using x-ray photoemission spectroscopy. The formation of B oxide and the reduction of Fe oxide at the bottom interface after thermal annealing near Ta=300°C were found to enhance the tunneling magnetoresistance ratio significantly. At the same time, an asymmetry of the conductance (dV∕dI) in the bias polarity and a local minimum of conductance in a positive bias state were measured which were attributed to the presence of a minority state at the bottom interface. The authors believe that the existence of the Bloch state was also responsible for the failure of the application of the Brinkman-Dynes-Rowell or Simmons models to the CoFeB∕MgO∕CoFeB junction.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.2779915