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dc.contributor.advisorPalai, Ratnakar
dc.contributor.authorAponte Rivera, Fernando J.
dc.description.abstractMultiferroic composite comprising of ferroelectric and ferromagnetic materials exhibit room temperature magnetoelectric (ME) effects greater than that of single-phase ME known to date. Spin capacitors have the potential to store both the electronic charge and magnetic spin that can produce conventional electric current and spin polarized current. The time evolution of spin polarized electrons injected into the piezoelectric material can be used for accurate sensing of ME fields. Ferromagnetic/Ferroelectric/Ferromagnetic (FM/FE/FM) tri-layer artificial multiferroelectric heterostructures in spin capacitor configuration were fabricated by sputtering ferromagnetic electrodes on lead zirconate titanate (PZT) substrates and depositing PZT on ferromagnetic sheets by Spray Pyrolysis. Magneto-dielectric (MD) measurements were carried out by a wide range of frequencies and magnetic fields at room temperature. We also compared the MD measurements with FM/PZT/Ag and Ag/PZT/Ag. A series of PZT barrier thickness were studied, including 200 μm and 1 mm, and a range of films of 1.4 μm to 7 μm. Ferroelectric polarization hysteresis loops were measured at different magnetic fields to determine the ME polarization of samples with nickel ferromagnets. The nickel spin capacitors have a very peculiar behavior compared to that of the iron and cobalt spin capacitors. Dielectric Peak behavior and positioning was studied for the samples. Different relaxation times are present, dependent on thickness and the presence of the FM material. As well, resonance is present in most samples at the range of ~1 MHz. Impedance spectroscopy show that the samples behave as brick-layer type, having grains and grain boundary interaction, with grain being the main driving factor. The Spray Pyrolysis deposition of PZT on ferromagnetic sheets was successful and yielded results similar of that given by the PZT pre-made substrates.en_US
dc.description.sponsorshipNSF-DMR1410869 NSF-PREM 1827622en_US
dc.rightsAttribution-NonCommercial-NoDerivs 3.0 United States*
dc.subject.lcshDielectrics--Magnetic propertiesen_US
dc.subject.lcshFerromagnetic materialsen_US
dc.subject.lcshImpedance spectroscopyen_US
dc.titleField and frequency dependence of ferroelectric-ferromagnetic multilayer heterostructuresen_US
dc.rights.holder© 2021 Fernando J. Aponte Riveraen_US
dc.contributor.committeeKatiyar, Ram
dc.contributor.committeeCabrera, Carlos
dc.contributor.campusUniversity of Puerto Rico, Río Piedras Campusen_US
dc.description.graduationSemesterSummer (3rd Semester)en_US
dc.description.graduationYear2021en_US Physicsen_US

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Attribution-NonCommercial-NoDerivs 3.0 United States
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 3.0 United States