Regensburg 2002 – scientific programme

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MA: Magnetismus

MA 7: Spinabhängige Transportphänomene II

MA 7.7: Talk

Tuesday, March 12, 2002, 11:00–11:15, H22

Assisted Tunneling and Spin Fluctuations in Ferromagnetic Tunnel Junctions — •Christian Schmidt, Jens Siewert, and Klaus Richter — Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg

In recent experiments on ferromagnetic tunnel junctions, a pronounced zero-bias anomaly has been found [1]. This phenomenon strongly suggests a coupling of the tunneling electrons to other degrees of freedom.

In mesoscopic systems, it is well known how to describe single-electron tunneling assisted by the bosonic degrees of freedom of an electromagnetic environment, the so-called P(E) theory [2]. In particular, this approach explains the zero-bias anomalies found in the I−V characteristics of mesoscopic tunnel junctions.

We propose an analogous description for assisted tunneling between ferromagnetic electrodes with spin-wave excitations representing the bosonic environment.

[1] S. Kreuzer, PhD Thesis, University of Regensburg, 2001.

[2] G.L. Ingold and Yu.V. Nazarov, in Single Charge Tunneling, edited    by H. Grabert and M.H. Devoret (Plenum, New York, 1992),    Chap.2.