| To regulate the magnetic,optical and electric properties of materials by electric field is of great significance for enriching material functionality and developing new devices.It has achieved great success in the semiconductor industry.In the process of regulating the properties of metal films by an electric field,the coulomb shielding effect by the high carrier concentration limits the modulation only to ultra-thin metal films.Electric-field induced ion migration is a more effective method to regulate the properties of metal films.Recently,H+,because of its small ionic radius and high diffusion coefficient,is expected to replace traditional ions such as O2-and Li+,providing a new approach for ion migration regulation of material properties.Previous studies have shown that many metals not only have decent characteristics of storing hydrogen but also their magnetic,optical,or electrical properties might change with hydrogen absorbing,which provides a basis for regulating the properties of metal films by electric-field-induced H+migration.Applying the electric field to induce H+migration can regulate the physical properties of metal films safely,rapidly,and reversibly,which has little damage to metal films and avoids using of high-pressure hydrogen.Our research in this thesis starts from the regulation method of H+ migration induced by electric field,and focuses on ferromagnetic rare earth-transition metal alloy GdxFe100-x films and hydrogen storage metal Mg films.Finally,the magnetic properties of GdxFe100-x films and the optical properties of Mg films were regulated in devices with different structures,and the influencing factors on the device performance were discussed.The main contents are summarized as follows:(1)Amorphous GdxFe100-x films with different stoichiometric ratios were prepared by magnetron sputtering technology and the composition was determined by electron probe technique.The characterization of their magnetic properties showed that thin films had perpendicular magnetic anisotropy when the mole ratio of Gd was between 21.2%-27.6%,and room temperature compensation point appeared when the mole ratio was between 25%～26.2%.As the compensation field approached room temperature,the saturation magnetization decreased and the coercive field increased.At the same time,the pattern of domain wall turnover was transformed from magnetization reversal induced by multiple nucleation points to domain wall displacement.(2)Using GdxFe100-x films as the channel,in-plane Hall bar devices gated by DEME-TFSI ionic-liquid and all-solid-state multilayer devices based on GdOx film electrolyte were fabricated and studied.Under high gating electric field,the absorbed water in electrolytes could be decomposed.As a result,the saturation magnetization,coercivity,magnetic domain and other magnetic properties of GdxFe100-x films would be rapidly regulated by driving H+into/out of GdxFe100-x films.And electric field controlled 180° reversible switching of magnetization direction in GdxFe100-x solid-state devices was realized.(3)Mg films with decent crystallinity were prepared by using magnetron sputtering technology.And multilayer devices with Ta/Mg/Pd/GdOx/Pd and Ta/Mg/Pd/GdOx/Au structures were fabricated using Pd and Au as top electrodes,respectively.By applying an electric field to the devices to generate H+and drive them into and out of Mg films,the optical transmission of Mg films was regulated.It was found that different top electrodes could induce different regulation effects.Compared with Au electrode,the devices with Pd electrode could reversibly regulate the transmittance of Mg film,and the changes of transmittance were more than 10%. |
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