IMF2017

Single phase multiferroic materials, that present typical ferroelectric ordering coexisting with magnetic ordering, are being intensively investigated, viewing to the coupling between spontaneous polarization and magnetization (magnetoelectric effect - ME). Multiferroic and photovoltaics materials have traditionally been investigated separately, although the coupling between light absorption and ferroelectricity has been known for years. Multiferroics may present a bandgap that is significantly lower than that of classical ferroelectrics, due to the pronounced electron-electron coupling, allowing combining ferroelectric properties with a low bandgap semiconductor material offering excellent options to tune photovoltaic properties. The efficiency of light conversion to electric energy (photovoltaic effect) in these materials can be modified by new techniques of synthesis, by suitable doping and sample conformation. In this presentation will be presented discussed semiconductor e photovoltaic properties of some lead free (KNN) and led based (PFN) multiferroics bulk and thin films. High density bulk ceramics samples were obtained through conventional or Spark Plasma Sintering technique (SPS). Thin films were grown by RF sputtering. Electric dielectric and photovoltaic properties have been investigated submitting the samples to different oxidation treatments, which allow changing the amount of oxygen vacancies generated during the sintering. Transport properties of domains and domain walls were investigated macroscopically, with conventional I-V techniques, and microscopically, using conductive atomic force microscopy (c-AFM). UV-Vis spectra of surface reflection revealed a remarkable dependence of the light absorption and, consequently, in the optical bandgap on the processing procedure.