Electric and chemical manipulation of magnetic anisotropy of ultrathin ferromagnetic films

Abstract : Spintronics is primarily based on the precise control of a nanostructure magnetization direction, are becoming increasingly important issues in device miniaturization. One line of research is tailoring the magnetic anisotropy energy (MAE) of the nanostructure. A second line aims at manipulating the magnetization through the magneto-electric coupling effect (MEC). In this work, influences of surface chemistry and influences of electric field on the MAE of the ferromagnetic thin films (cobalt) have been studied separately by an all electrochemical approach, compared to solid state devices. The electrolyte environments allow us to deposit ultraflat 2D epitaxial thin films; modify the surface chemistry easily; and apply a relative large and uniform electric field through a naturally formed defects-free ionic dielectric double layer. Oxidation of the Co was achieved in an alkaline electrolyte. The structures of different oxide layers were investigated via DFT calculations and electrochemical charge. Their influences on the MAE were studied in real time by in-situ polar magneto-optic Kerr effect (MOKE) measurements. Influences of other molecular layers linked by –S, -C, -N were also investigated. MEC effects only due to the electric field of Co thin films covered by different molecular layers were characterized quantitatively, and dependence of MEC effect with the surface chemistry was observed. Furthermore, modifications of MAE of Pd-Co systems induced by H ad/absorption were analyzed as well. In most cases, theoretic hypothesis were suggested to explain the experimental results.
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Submitted on : Wednesday, November 4, 2015 - 12:28:53 PM
Last modification on : Wednesday, March 27, 2019 - 4:18:02 PM
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  • HAL Id : tel-01224224, version 1

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Nan Di. Electric and chemical manipulation of magnetic anisotropy of ultrathin ferromagnetic films. Physics [physics]. Ecole Polytechnique, 2015. English. ⟨tel-01224224⟩

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