LiNbO3-Type InFeO3: Room-Temperature Polar Magnet without Second-Order Jahn-Teller Active Ions
Artikel i vetenskaplig tidskrift, 2016

Great effort has been devoted to developing single-phase magnetoelectric multiferroics, but room-temperature coexistence of large electric polarization and magnetic ordering still remains elusive. Our recent finding shows that such polar magnets can be synthesized in small-tolerance-factor perovskites AFeO(3) with unusually small cations at the A-sites, which are regarded as having a LiNbO3-type structure (space group R3c). Herein, we experimentally reinforce this finding by preparing a novel room-temperature polar magnet, LiNbO3-type InFeO3. This compound is obtained as a metastable quench product from an orthorhombic perovskite phase stabilized at 15 GPa and an elevated temperature. The structure analyses reveal that the polar structure is characterized by displacements of In3+ (d(10)) and Fe3+ (d(5)) ions along the hexagonal c-axis (pseudocubic [111] axis) from their centrosymmetric positions, in contrast to well-known perovskite ferroelectrics (e.g., BaTiO3, PbTiO3, and BiFeO3) where d(0) transition-metal ions and/or 6s(2) lone-pair cations undergo polar displacements through the so-called second-order Jahn-Teller (SOJT) distortions. Using density functional theory calculations, the electric polarization of LiNbO3-type InFeO3 is estimated to be 96 mu C/cm(2) along the c-axis, comparable to that of an isostructural and SOJT-active perovskite ferroelectric, BiFeO3 (90-100 mu C/cm(2)). Magnetic studies demonstrate weak ferromagnetic behavior at room temperature, as a result of the canted G-type antiferromagnetic ordering of Fe3+ moments below T-N similar to 545 K. The present work shows the functional versatility of small-tolerance-factor perovskites and provides a useful guide for the synthesis and design of room-temperature polar magnets.

Författare

K. Fujita

Kyoto University

T. Kawamoto

Kyoto University

I. Yamada

Japan Science and Technology Agency

Osaka Prefecture University

O. Hernandez

Universite de Rennes 1

N. Hayashi

Research Institute For Production Development

H. Akamatsu

Tokyo Institute of Technology

Pennsylvania State University

W. Lafargue-Dit-Hauret

Universite de Rennes 1

X. Rocquefelte

Universite de Rennes 1

M. Fukuzumi

Hyogo Prefectural Institute of Technology

P. Manuel

ISIS Facility

A. J. Studer

Australian Nuclear Science and Technology Organisation

Christopher Knee

Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

K. Tanaka

Kyoto University

Chemistry of Materials

0897-4756 (ISSN) 1520-5002 (eISSN)

Vol. 28 6644-6655

Ämneskategorier

Materialkemi

DOI

10.1021/acs.chemmater.6b02783