Alekhin A, Razdolski I, Berritta M, Bürstel D, Temnov V, Diesing D, Bovensiepen U, Woltersdorf G, Oppeneer P M, Melnikov A
Institute of Molecules and Materials of Le Mans, CNRS UMR 6283, 72085 Le Mans, France.
J Phys Condens Matter. 2019 Mar 27;31(12):124002. doi: 10.1088/1361-648X/aafd06. Epub 2019 Jan 9.
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(0 0 1) 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.
我们展示了一种通过在Au/Fe/MgO(0 0 1)异质结构中激光诱导注入热自旋极化电子来激发金中可观磁光效应的新方法。它基于Fe/Au界面的能量和自旋相关电子透射率，该界面作为在Fe中光学激发的非热电子的自旋滤波器。我们表明，多数电子穿过界面后，以约1 nm fs的速度（接近费米速度）在金层中传播，衰减长度约为100 nm。自旋注入具有超快功能且无需强外部磁场，导致金产生明显的磁光响应。我们基于瞬态复磁光克尔效应响应的相位发展了一种形式体系，并在包括我们的从头算在内的大量关于金的实验和理论磁光克尔效应研究中证明了其稳健性。我们的工作引入了一种灵活的工具，可在飞秒时间尺度上操纵金属的磁光特性，这在有源磁光子学、等离子体学和自旋电子学方面具有很高的潜力。
