Room temperature ferroelectricity and ferromagnetism in Ni-substituted Bi5Ti3FeO15

Abstract

Aurivillius-type bismuth layer-structured ferroelectric (BLSF) Bi5Ti3FeO15 (BTF) has recently attracted considerable attention as a typical multiferroic material because ferroelectric and magnetic orders coexist, but bulk BTF exhibits antiferromagnetic (AFM) orders and negligible intrinsic magnetoelectric (ME) coupling effects. In this study, nickel-substituted Bi5Ti3FeO15 (Bi5Ti3Fe0.5Ni0.5O15, abbreviated as BTF-Ni) was synthesized using a solid-state reaction method to explore and enhance both the magnetic and ferroelectric properties of BTF. Polarization-electric field P-E loops indicate that the BTF-Ni exhibits considerable maximum polarization P m of 11.9 μC/cm2 and remnant polarization P r of 5.8 μC/cm2, but still keeps a very high ferroelectric Curie temperature (FE T c) of 1029 K, which are much superior to those of pure BTF. Moreover, magnetization-magnetic field M-H loops indicate that BTF-Ni exhibits significant ferromagnetic properties with a large saturation magnetization M s of 60 memu/g, low coercive field H c of 31 Oe at room temperature, and a high ferromagnetic Curie temperature (FM T c) of 698 K, whereas pure BTF has an antiferromagnetic Néel temperature (T N) of 80 K. Our work suggests that nickel-substituted BTF is a potential room-temperature magnetoelectric multiferroic material.