Spatially confined electronic materials for resistive switching devices

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My previous and current research has been focused on synthesis of thin films and micro-bridges of magnetic oxides (manganites) and studies of their electronic/material properties. These studies led to discovery of unusual material properties (such as, anisotropic magnetoresistance AMR) in these materials. Large AMR can be used in magnetic switching devices. I want AMR to reach colossal size in micro-bridges. My plans to increase the size of AMR include modification of nano-bridges of manganite films using an electron beam, as well as subjecting these bridges to stress (in piezoelectric devices). These procedures could change properties (electronic phase separation) in bridges of these materials. I am planning to use my experience with manganite materials and techniques to investigate the mechanisms responsible for unusual transport properties (resistive switching (RS)) in dielectric oxide films. Typically, the change in resistance in the dielectrics is "non-volatile" i.e., the resulting resistance can be maintained for a long time after the removal of the applied electric field. It was suggested that electric field-induced RS could be used for the next-generation random-access memory devices. I am planning first to investigate prototypical multilayer dielectric systems. There are many “parallels” between these oxides and manganites. Migration of defects and its formation are very sensitive to the shear stress in both materials. Also, the electrical transport in the dielectric oxides appears to be caused by the filamentary percolation conductivity, which is like that observed in manganites. I want to understand formation of these filaments as well as their influence on RS in dielectric oxides. I want to understand filaments in these dielectrics, the activation energy of its formation, and its structural nature. I want to answer important question; Are these filaments formed by extended defects or electro-migration of oxygen defects? My research plan is to investigate changes in the electric/structural material properties of the different types of dielectric oxide multilayer systems using piezoelectric (PMNT-based stress producing) devices, and ionic-liquid based devices capable of producing large electric field. Using this techniques, I want to separate effects due to the extended defects from those due to the electro-migration of oxygen defects in the formation of filamentary RS. The number of extended defects depends strongly on the shear stress. On the other hand, the electro-migration of defects depends strongly on the electric field. Therefore, the applied stress and electric field could help me to “tune” the dielectric system devices to conditions capable of producing large RS. The goal of this research could allow me to produce new type of devices for RS switching purposes, as well as to understand in more detail the mechanism of RS.