TY - JOUR
KW - Transmission electron microscopy
KW - Scanning electron microscopy
KW - Iron compounds
KW - Polarization
KW - Bismuth compounds
KW - Ferroelectricity
KW - Ferroelectric polarization
KW - Bismuth ferrite
KW - High resolution transmission electron microscopy
KW - Scanning transmission electron microscopy
KW - Doping (additives)
KW - Semiconductor doping
KW - Differential phase contrast
KW - Differential phase contrast imaging
KW - Functional properties
KW - Periodic distortions
KW - Polarization gradients
AU - M Campanini
AU - R Erni
AU - C.-H Yang
AU - Ramamoorthy Ramesh
AU - M.D Rossell
AB - The ultimate challenge for the development of new multiferroics with enhanced properties lies in achieving nanoscale control of the coupling between different ordering parameters. In oxide-based multiferroics, substitutional cation dopants offer the unparalleled possibility to modify both the electric and magnetic properties at a local scale. Herein it is demonstrated the formation of a dopant-controlled polar pattern in BiFeO3 leading to the spontaneous instauration of periodic polarization waves. In particular, nonpolar Ca-doped rich regions act as spacers between consecutive dopant-depleted regions displaying coupled ferroelectric states. This alternation of layers with different ferroelectric state creates a novel vertical polar structure exhibiting giant polarization gradients as large as 70 μC cm-2 across 30 Å thick domains. The drastic change in the polar state of the film is visualized using high-resolution differential phase-contrast imaging able to map changes in ferroelectric polarization at atomic scale. Furthermore, a periodic distortion in the Fe - O - Fe bonding angle suggests a local variation in the magnetic ordering. The findings provide a new insight into the role of doping and reveal hitherto unexplored means to tailor the functional properties of multiferroics by doping engineering. © 2018 American Chemical Society.
BT - Nano Letters
DO - 10.1021/acs.nanolett.7b03817
LA - eng
M1 - 2
N1 - cited By 15
N2 - The ultimate challenge for the development of new multiferroics with enhanced properties lies in achieving nanoscale control of the coupling between different ordering parameters. In oxide-based multiferroics, substitutional cation dopants offer the unparalleled possibility to modify both the electric and magnetic properties at a local scale. Herein it is demonstrated the formation of a dopant-controlled polar pattern in BiFeO3 leading to the spontaneous instauration of periodic polarization waves. In particular, nonpolar Ca-doped rich regions act as spacers between consecutive dopant-depleted regions displaying coupled ferroelectric states. This alternation of layers with different ferroelectric state creates a novel vertical polar structure exhibiting giant polarization gradients as large as 70 μC cm-2 across 30 Å thick domains. The drastic change in the polar state of the film is visualized using high-resolution differential phase-contrast imaging able to map changes in ferroelectric polarization at atomic scale. Furthermore, a periodic distortion in the Fe - O - Fe bonding angle suggests a local variation in the magnetic ordering. The findings provide a new insight into the role of doping and reveal hitherto unexplored means to tailor the functional properties of multiferroics by doping engineering. © 2018 American Chemical Society.
PB - American Chemical Society
PY - 2018
SP - 717
EP - 724
T2 - Nano Letters
TI - Periodic Giant Polarization Gradients in Doped BiFeO3 Thin Films
VL - 18
SN - 15306984
ER -