Temperature dependence of tunnel magnetoresistance in Co-Mn-Al/Al-oxide/Co-Fe junctions

Mikihiko Oogane, Jun Nakata, Hitoshi Kubota, Yasuo Ando, Akimasa Sakuma, Terunobu Miyazaki

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8 Citations (Scopus)


We investigated the temperature dependence of the tunnel magnetoresistance (TMR) effect in Co-Mn-Al/Al-oxide/Co-Fe tunnel junctions. The junction prepared without exposure to air during deposition showed very large TMR ratios of 65% at 10 K and 40% at room temperature. In contrast, the junction prepared with air exposure before and after Al-oxide layer fabrication showed a maximum TMR ratio of only 40% at a low temperature. Temperature dependences of tunnel conductance of these junctions were analyzed using a simple model that incorporates two contributions: elastic tunneling with decreasing spin polarization as temperature increases and spin-independent hopping tunneling through trap states in Al-oxide tunnel barriers. Results of analyses indicated that air exposure drastically reduced spin polarization and Curie temperature. It also created an inferior insulating layer at the Co-Mn-Al/Al-oxide interface.

Original languageEnglish
Pages (from-to)L760-L762
JournalJapanese Journal of Applied Physics
Issue number24-27
Publication statusPublished - 2005 Jun 24


  • Half-metal
  • Hausler alloy
  • Spin polarization
  • Tunnel magnetoreslstance


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