Magnetoresistance studies on Co/AlOX/Au and Co/AlOX/Ni/Au tunnel structures

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Abstract

We report on magnetoresistance (MR) studies on Co/AlOX/Au and Co/AlOX/Ni/Au magnetic tunnel junctions. In spite of the fact that the difference between the two samples is merely a 3 nm thick Ni layer, there is a sharp contrast in MR behavior indicating that the electronic structure at the interface between the ferromagnetic electrodes and the insulating barrier dominates the MR signal. The former sample exhibits a clear tunneling anisotropic MR (TAMR), with the characteristic correlation between resistance and current direction, in contrast to the latter sample which displays a conventional tunneling MR (TMR) dominated by the relative orientation between the magnetization directions of the two electrodes. In addition, the TAMR has a much stronger temperature dependence than the TMR, indicating a much faster drop-off of the tunneling density of states anisotropy than the tunneling electron spin polarization with increasing temperature. Finally, we propose a possible simple way to distinguish TAMR from normal TMR by measuring the resistance of the device at different angles of the external magnetic field.

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Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Condensed Matter Physics

Keywords

  • nickel, magnetisation, tunnelling magnetoresistance, magnetic thin films, gold, ferromagnetic materials, polarisation, electron spin, cobalt, aluminium compounds, band structure
Original languageEnglish
Article number203107
JournalApplied Physics Letters
Volume93
Issue number20
Publication statusPublished - 2008
Publication categoryResearch
Peer-reviewedYes