Tunneling spectroscopy and magnon excitation in Co2FeAl/MgO/Co–Fe magnetic tunnel junctions

Ebke, Daniel; Drewello, Volker; Schäfers, Markus; Reiss, Günter; Thomas, Andy
December 2009
Applied Physics Letters;12/7/2009, Vol. 95 Issue 23, p232510
Academic Journal
Magnetic tunnel junctions with the Heusler compound Co2FeAl as the soft electrode are prepared. Pinned Co–Fe is used as the hard reference electrode. The junctions show a high tunnel magnetoresistance ratio of 273% at 13 K. The electronic transport characteristics are investigated by tunneling spectroscopy—dI/dV and d2I/dV2 are discussed. In the parallel magnetic state the tunneling spectra are asymmetric with respect to the bias voltage, with a pronounced bias-independent region. In the antiparallel state the dependence on bias voltage is much stronger and the curves are symmetric. The findings can be explained with a gap in the minority density of states of Co2FeAl.


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