5 research outputs found
Engineering room-temperature multiferroicity in Bi and Fe codoped BaTiO3
Fe doping into BaTiO3, stabilizes the paraelectric hexagonal phase in place
of the ferroelectric tetragonal one [P. Pal et al. Phys. Rev. B, 101, 064409
(2020)]. We show that simultaneous doping of Bi along with Fe into BaTiO3
effectively enhances the magnetoelectric (ME) multiferroic response (both
ferromagnetism and ferroelectricity) at room-temperature, through careful
tuning of Fe valency along with the controlled-recovery of
ferroelectric-tetragonal phase. We also report systematic increase in large
dielectric constant values as well as reduction in loss tangent values with
relatively moderate temperature variation of dielectric constant around
room-temperature with increasing Bi doping content in Ba1-xBixTi0.9Fe0.1O3
(0<x<0.1), which makes the higher Bi-Fe codoped sample (x=0.08) promising for
the use as room-temperature high-k dielectric material. Interestingly, x=0.08
(Bi-Fe codoped) sample is not only found to be ferroelectrically (~20 times)
and ferromagnetically (~6 times) stronger than x=0 (only Fe-doped) at room
temperature, but also observed to be better insulating (larger bandgap) with
indirect signatures of larger ME coupling as indicated from anomalous reduction
of magnetic coercive field with decreasing temperature. Thus, room-temperature
ME multiferroicity has been engineered in Bi and Fe codoped BTO (BaTiO3)
compounds.Comment: 16 pages, 17 figure
Origin and tuning of room-temperature multiferroicity in Fe-doped
Simultaneous coexistence of room-temperature ferromagnetism and ferroelectricity in Fe-doped BaTiO (BTO) is intriguing, as such Fe doping into tetragonal BTO, a room-temperature ferroelectric, results in the stabilization of its hexagonal polymorph which is ferroelectric only below ∼80K. Here, we investigate its origin and show that Fe-doped BTO has a mixed-phase room-temperature multiferroicity, where the ferromagnetism comes from the majority hexagonal phase and a minority tetragonal phase gives rise to the observed weak ferroelectricity. In order to achieve majority tetragonal phase (responsible for room-temperature ferroelectricity) in Fe-doped BTO, we investigate the role of different parameters which primarily control the paraelectric hexagonal phase stability over the ferroelectric tetragonal one and identify three major factors, namely the effect of ionic size, Jahn-Teller (JT) distortions, and oxygen-vacancies, to be primarily responsible. The effect of ionic size which can be qualitatively represented using the Goldschmidt's tolerance factor seems to be the major dictating factor for the hexagonal phase stability. The understanding of these factors not only enables us to control them but also to achieve a suitable codoped BTO compound with enhanced room-temperature multiferroic properties