Spin-Dependent Inelastic Electron Tunneling Spectroscopy of Magnetic Tunnel Junctions

概要

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We investigated the nature of spin dependent scattering by employing inelastic electron tunneling spectroscopy in magnetic tunnel junctions. In this work we introduced a comparable quantity represented as $(\mathrm{d}^{2}V/\mathrm{d}I^{2})/(\mathrm{d}V/\mathrm{d}I)$ by simultaneous measurements of the $\mathrm{d}V/\mathrm{d}I$ and $\mathrm{d}^{2}V/\mathrm{d}I^{2}$ curves. In each junction we measured, a zero bias anomaly was observed close to the Fermi energy ($\pm 2$ mV). Furthermore, a relatively large spin dependent scattering occurred around $\pm 18$ mV. These peaks and zero bias anomalies were the primary cause of the drop of the tunneling magnetoresistance (TMR) ratio as the bias voltage was applied. Furthermore, insertion of a normal metal between the insulator and ferromagnetic metal was examined. Silver exhibited a reduction of spin dependent scattering, while excess aluminum induced a large zero bias anomaly.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-11-15