Doctor of Philosophy (PhD)
Electrical and Computer Engineering
First Advisor's Name
First Advisor's Committee Title
Second Advisor's Name
Jean H. Andrian
Second Advisor's Committee Title
Third Advisor's Name
Stavros V. Georgakopoulos
Third Advisor's Committee Title
Fourth Advisor's Name
Fourth Advisor's Committee Title
Fifth Advisor's Name
Fifth Advisor's Committee Title
Sixth Advisor's Name
Osama A. Mohammed
Sixth Advisor's Committee Title
Colossal Magnetoelectric Effect, CoFe2O4-BaTiO3, NiFe2O4-BaTiO3, Coreshell Nanostructures, Magnetoelectric Nanoparticles
Date of Defense
The greatly increased interest in magnetoelectric materials over the last decade is due to their potential to enable next-generation multifunctional nanostructures required for revolutionizing applications spanning from energy-efficient information processing to medicine. Magnetoelectric nanomaterials offer a unique way to use a voltage to control the electron spin and, reciprocally, to use remotely controlled magnetic fields to access local intrinsic electric fields. The magnetoelectric coefficient is the most critical indicator for the magnetoelectric coupling in these nanostructures. To realize the immense potential of these materials, it is necessary to maximize the coefficient. Therefore, the goal of this PhD thesis study was to create a new paradigm for the synthesis and characterizations of magnetoelectric materials which would allow to create a new dynasty of nanostructures required for unlocking all their unprecedented capabilities. Coreshell nanostructures with a 0-3 connectivity scheme, i.e. (Co, Ni) Fe2O4-BaTiO3, represent the most studied system. Their relatively low coefficient value is often attributed to the problem known as the dielectric leakage, which is present during the traditional powder form measurements of the coefficient. To overcome this problem, we implemented a novel approach to measure the coefficient at a single-nanoparticle level. Using a scanning probe microscopy, we entirely eliminated the interparticle interaction and thus the leakage problem. The success of this approach was underscored by achieving, for the first time, perfect crystal lattice matching between the magnetostrictive core and the piezoelectric shell of the coreshell configuration, as confirmed via transmission electron microscopy. As a result, this study led to the coefficient value for CoFe2O4-BaTiO3 nanoparticles of above 5 V cm-1 Oe-1, almost two orders of magnitude higher than the highest reported value elsewhere. Additionally, we for the first time demonstrated three different regions which are barium titanate shell, the interfacial transition, and the cobalt ferrite core, respectively, by imaging a half-grown coreshell nanoparticle with atomic force microscopy. Alternating gradient and cryogenic vibrating sample magnetometry were utilized to study the magnetic properties of materials. X-ray diffraction was employed to bespeak that the crystallinity of barium titanate is enhanced along with the increase of cobalt ferrite dopant on account of heterogeneous nucleation.
Previously Published In
Wang, P., Zhang, E., Toledo, D., Smith, I. T., Navarrete, B., Furman, N., ... & Khizroev, S. (2020). Colossal Magnetoelectric Effect in Coreshell Magnetoelectric Nanoparticles. Nano Letters.
Wang, Ping, "Nanoelectronic Applications of Magnetoelectric Nanostructures" (2020). FIU Electronic Theses and Dissertations. 4515.
Biology and Biomimetic Materials Commons, Biomedical Commons, Ceramic Materials Commons, Electrical and Electronics Commons, Electromagnetics and Photonics Commons, Electronic Devices and Semiconductor Manufacturing Commons, Nanotechnology Fabrication Commons, Semiconductor and Optical Materials Commons
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).