Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 36: Magnetic Heusler Compounds II

MA 36.5: Talk

Thursday, March 29, 2012, 11:15–11:30, H 1012

Tunneling spectroscopy of the Heusler compound Co₂MnGa — •Elena Arbelo Jorge, Mathias Kläui, and Martin Jourdan — Institut für Physik, Johannes Gutenberg Universität Mainz, Staudingerweg 7, 55128 Mainz

Planar tunneling junctions with a Heusler electrode are typically used as tunneling magnetoresistance (TMR) devices. The obtained TMR can be associated with the spin polarization of the Heusler compound applying the Julliere model if amorphous AlO_x is used as a tunneling barrier[1].

Here we use planar tunneling junctions for investigations of the density of states of the Heusler compound Co₂MnGa, which is compared to the results of photoemission spectroscopy (UPS) and band structure calculations.

Planar Co₂MnGa-AlO_x-Au (or CoFe) junctions were prepared by rf-sputtering and photolithographic patterning. With the ferromagnetic counter electrode CoFe used for TMR-devices the bias dependent differential conductivity dI/dV(V) of the junctions shows a pronounced V-shape which we associate with strong contributions of magnon excitations to the tunneling process. These excitations hide the DOS features of the Heusler electrode. However, using Au as the counter electrode characteristic features of the Heusler DOS were identified which are consistent with the results obtained by UPS.

[1] e. g. C. Herbort, E. Arbelo Jorge, and M. Jourdan, Appl. Phys. Lett. 94, 142504 (2009).

Financial support by the DFG-FG559 (Jo404/4-1) is acknowledged.