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TT: Fachverband Tiefe Temperaturen

TT 20: Transport: Spincaloric Transport (jointly with MA)

TT 20.8: Vortrag

Montag, 11. März 2013, 17:00–17:15, H22

Ab initio investigations on the magnetothermopower of thin Co/Cu multiple spin-valves — •Voicu Popescu and Peter Kratzer — Faculty of Physics, University Duisburg-Essen, Duisburg, Germany

We have modelled multiple spin-valve configurations by stacking Co and Cu layers of various thickness and number of repetitions. Theoretical investigations on their magneto-thermoelectric properties were performed by calculating the conventional and magnetic Seebeck coefficient using a spin-polarized relativistic implementation of the Landauer-Büttiker conductance formula within the framework of Korringa-Kohn-Rostoker method.

In line with experimental expectations, we find that the anti-parallel (AP) alignment of the adjacent Co layers is characterized by a much larger Seebeck coefficient than the parallel (P) configuration: from 1−2 µV/K in the P-case, the AP Seebeck coefficient can reach as much as 10 µV/K at room temperature. A correspondence between these values and the giant magneto-resistance characteristic to the Co/Cu spin valves could thus be established.

We show that an increase in the thickness of the Co layer further enhances the magnetothermopower whereas the Cu layer thickness variation has a negligible effect. In addition, we investigate the magnetic anisotropy in the Seebeck coefficient for these systems, by changing the magnetization orientation from parallel to perpendicular to the current. Our results suggest that a strong Seebeck magnetic anisotropy could be detected in typical GMR elements.