Magneto-optical properties of Au upon the injection of hot spin-polarized electrons across Fe/Au(001) interfaces

A. Alekhin; I. Razdolski; M. Berritta; D. Bürstel; V. Temnov; D. Diesing; U. Bovensiepen; G. Woltersdorf; P. M. Oppeneer; A. Melnikov

doi:10.1088/1361-648x/aafd06

arXiv · 1810.12237

Magneto-optical properties of Au upon the injection of hot spin-polarized electrons across Fe/Au(001) interfaces

A. Alekhin·I. Razdolski·M. Berritta·D. Bürstel·V. Temnov·D. Diesing·U. Bovensiepen·G. Woltersdorf·P. M. Oppeneer·A. Melnikov

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Abstract

We demonstrate a novel method for the excitation of sizable magneto-optical effects in Au by means of the laser-induced injection of hot spin-polarized electrons in Au/Fe/MgO(001) heterostructures. It is based on the energy- and spin-dependent electron transmittance of Fe/Au interface which acts as a spin filter for non-thermalized electrons optically excited in Fe. We show that after crossing the interface, majority electrons propagate through the Au layer with the velocity on the order of 1 nm/fs (close to the Fermi velocity) and the decay length on the order of 100 nm. Featuring ultrafast functionality and requiring no strong external magnetic fields, spin injection results in a distinct magneto-optical response of Au. We develop a formalism based on the phase of the transient complex MOKE response and demonstrate its robustness in a plethora of experimental and theoretical MOKE studies on Au, including our ab initio calculations. Our work introduces a flexible tool to manipulate magneto-optical properties of metals on the femtosecond timescale that holds high potential for active magneto-photonics, plasmonics, and spintronics.

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A. Alekhin, I. Razdolski, M. Berritta, D. Bürstel, V. Temnov, D. Diesing, U. Bovensiepen, G. Woltersdorf, P. M. Oppeneer, A. Melnikov. 2018-10-29. Magneto-optical properties of Au upon the injection of hot spin-polarized electrons across Fe/Au(001) interfaces. https://doi.org/10.1088/1361-648x/aafd06

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