Influence of annealing on spin-dependent tunneling characteristics of fully epitaxial Co2MnGe/MgO/Co50Fe50 magnetic tunnel junctions

Taira, Tomoyuki; Ishikawa, Takayuki; Itabashi, Naoki; Matsuda, Ken-ichi; Uemura, Tetsuya; Yamamoto, Masafumi
February 2009
Applied Physics Letters;2/16/2009, Vol. 94 Issue 7, pN.PAG
Academic Journal
We found that the tunnel magnetoresistance ratio of fully epitaxial Co2MnGe/MgO/Co50Fe50 magnetic tunnel junctions (MTJs) increased discontinuously and significantly from 92% at room temperature (RT) (244% at 4.2 K) for Ta of 475 °C to 160% at RT (376% at 4.2 K) for Ta of 500 °C, where Ta is the temperature at which the MTJ trilayer was in situ annealed right after deposition of the upper electrode. We also found that the dI/dV versus V characteristics for the parallel and antiparallel magnetization configurations changed discontinuously and markedly with increasing Ta from 475 °C or less to 500 °C or higher. These significant changes are discussed in terms of a possible change in the spin-dependent interfacial density of states.


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