Manipulation Of Exchange Bias Via Electric Field Driven Ion Implantation In All-Solid-State Li-Ion Redox Capacitor Structure

The exchange bias effect is that the ferromagnetic materials are unidirectional pinned at the interface by the antiferromagnetic materials.Specifically,the hysteresis loop of the ferromagnetic materials is shifted horizontally relative to the center point.The ferromagnetic layer with exchange bias effect is an indispensable part of the device,which acts as a reference layer in the spin electronics device.How to effectively control the exchange bias effect in devices has been one of the key research directions in the field of spintronics.In this thesis,we study the exchange bias effect of ion implantation driven by electric field based on all solid state lithium-ion capacitor.The main research contents include:(1)Using Li Co O₂as the source of lithium ion,the effect of electric field driven Li ion implantation on the exchange bias effect in Co/Co₃O₄ heterojunction was studied.Due to the small atomic radius of lithium ion,it can easily penetrate into Co₃O₄ film under the action of external electric field.The results of transmission electron microscope and Raman spectrum show that Li ion insertion and desorption can reversibly regulate the microstructure and co valence of antiferromagnetic Co₃O₄ films,and then regulate the antiferromagnetic ordering degree of Co₃O₄films under the Neel temperature(T_N=40 K).The regulation of antiferromagnetic order of Co₃O₄ thin film by electric field driven Li ion implantation results in reversible and non-volatile regulation of exchange bias effect in Co/Co₃O₄ heterojunction,and the regulation can maintain good stability after 300 cycles.(2)An antiferromagnetic material Ni O with higher Neel temperature(T_N=520 K),was selected to study the effect of electric field driven Li ion implantation on exchange bias in Co/Ni O heterojunction at room temperature.It is found that the exchange bias effect in the Co/Ni O heterojunction can be reversible and non-volatile regulated by the electric field driven Li injection into Ni O.And after 1000 cycles,the regulation can maintain good stability.Compared with the Co/Co₃O₄ system,the exchange bias effect in the Co/Ni O heterojunction can occur at room temperature and be effectively controlled by implanted ions.The results of this thesis not only provide a new way for the reversible and non-volatile electric field to control the exchange bias effect,but also show that the electric field driven ion implantation can be used to adjust the microstructure and magnetic properties of magnetic materials based on the chemical reactions of lithium,such as insertion,alloying and displacement reactions.