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DF: Fachverband Dielektrische Festkörper

DF 14: Thermoelectric and Spincaloric Transport in Nanostructures

DF 14.5: Hauptvortrag

Mittwoch, 13. März 2013, 11:30–12:00, H1

Tunneling magneto thermopower in magnetic tunnel junction nanopillars — Niklas Liebing¹, Santiago Serrano-Guisan^1,2, Patryk Krzysteczko¹, Karsten Rott³, Günter Reiss³, Jürgen Langer⁴, Berthold Ocker⁴, and •Hans Werner Schumacher¹ — ¹PTB, Braunschweig, Germany — ²INL, Braga, Portugal — ³U. Bielefeld, Bielefeld, Germany — ⁴Singulus AG, Kahl am Main, Germany

Magneto-thermoelectric properties of magnetic nanostructures have attracted a broad attention over the last years. However only recenly first studies of the magneto-thermoelectric properties of magnetic tunnelling junctions (MTJ) have been published. These studies included the prediction [1] and experimental observation [2-4] of tunnelling magneto thermo power (TMTP). In this talk we will discuss our recent results on TMTP of CoFeB/MgO/CoFeB MTJ nanopillars [3]. For TMTP measurements the thermally induced voltage V_T across the MTJ is measured as function of magnetic field. The thermopower signal V_T scales linearly with the temperature gradient and reveals a similar spin dependence as the TMR. We observe a spin-dependent change of the Seebeck coefficient of up to 0.2 mV/K and a correspondingly large TMTP ratio of up to 90 per cent. This might enable future spin-caloritronics applications of CoFeB/MgO/CoFeB based MTJs. [1] M. Czerner et al. Phys. Rev. B 83, 132405 (2011), [2] M. Walter et al., Nature Mat. 10, 742 (2011), [3] N. Liebing et al. PRL 107, 177201 (2011), [4] W. Lin et al., Nat. Comm. 3, 744 (2012).