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The design and control of magnetic anisotropy have been required for developing small size and low power consumption spintronics devices. Recently, electric field (EF) modulation of coercivity and magnetic anisotropy energy (MAE) has been reported for diluted magnetic semiconductors [1] and metallic systems [2,3]. The EF control of MAE is a key technique for realizing magnetic reversal with low energy consumption in spintronics devices. In this work, the magnetic anisotropy and its EF effect have been studied by the first principles electronic structure calculation. We used the pseudopotential planewave method with the fully relativistic version. In order to impose the EF, the scheme of effective screening medium method was employed [4]. We estimated MAE and its EF variation for several surface and interface systems (for examples, FePt and FeAu surface system and FePd, FePt and FeAu film capped with MgO). For the Fe-chain on Pt vicinal surface which is the largest system in our work, the estimated easy axis direction was almost agrees with the available experimental data. From our calculation, the important results were obtained to get larger EF effect. One of them was the significant enhancement of MAE modulation for the Fe-Pt thin films compared to Fe, FePd and FeAu thin films. We also investigated EF effects in MgO/Pt/Fe/Pt(001) film to reveal influences of the dielectric material. It was found that the ratio of MAE v.s. EF is almost proportional to the dielectric constant of dielectric materials. The material search for the EF effect on MAE is just beginning and the first principles approach is considerably very useful for such project. [1] D. Chiba et. al., Science 301, 943 (2003). [2] M. Weisheit et. al., Science 315, 349 (2007). [3] T. Maruyama et. al., Nature Nanotech. 4, 158 (2009). [4] M. Otani et. al., Phys. Rev. B 73, (2006) 115407. |
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