Ferroelectricity and multiferroicity in anti–Ruddlesden–Popper structures

Abstract

Combining ferroelectricity with other properties such as visible light absorption or long-range magnetic order requires the discovery of new families of ferroelectric materials. Here, through the analysis of a high-throughput database of phonon band structures, we identify a structural family of anti–Ruddlesden–Popper phases A4X2O (A=Ca, Sr, Ba, Eu, X=Sb, P, As, Bi) showing ferroelectric and antiferroelectric behaviors. The discovered ferroelectrics belong to the new class of hyperferroelectrics that polarize even under open-circuit boundary conditions. The polar distortion involves the movement of O anions against apical A cations and is driven by geometric effects resulting from internal chemical strains. Within this structural family, we show that Eu4Sb2O combines coupled ferromagnetic and ferroelectric order at the same atomic site, a very rare occurrence in materials physics.

Vacancy-Induced Niobate Perovskite-Tungsten Bronze Composite for Synergetic Tuning of Ferroelectricity and Band Gaps

“…The difference between the two symmetries was negligible for XRD reflections, especially when those intensities of the tungsten bronze phase were rather small. However, the polar P 4 bm was believed to be a preferred ground state of the tungsten bronze phase according to the hysteresis loop measured as well as to some similar examples predicted by calculations. − …”

Ca4Sb2O and Ca4Bi2O: two promising mixed-anion thermoelectrics

“… 30,31 Moreover, quite recently ferroelectric and antiferroelectric behaviours and applications to ferroelectric photovoltaics have been reported for this family of anti-Ruddlesden–Popper phases. 32 Inspired by this, we have investigated the p-type thermoelectric properties of two experimentally-reported mixed-anion oxypnictides with similar composition, viz. Ca 4 Sb 2 O and Ca 4 Bi 2 O.…”

Broken-gap type-III band alignment in monolayer halide perovskite/antiperovskite oxide van der Waals heterojunctions

“…For example, the space group of Ba 4 OP 2 is Abnm obtained in experiments, 42 but the anti-ferroelectric Cmce group is preferable in theory. 28 Here, we only consider the I 4/ mmm structure to discuss the related physical properties in the rest of the paper.…”

“…22,23 In addition to antiperovskite nitrides, antiperovskite oxides (i.e., anti-Ruddlesden-Popper phases X 4 OA 2 (X 2+ = Ca 2+ , Sr 2+ , Ba 2+ , Eu 2+ ; A 3− = P 3− , As 3− , Sb 3− , Bi 3− ) have also been reported to exhibit attractive ferroelectric/antiferroelectric, thermoelectric, and optoelectronic properties. [24][25][26][27][28] Although both antiperovskite semiconductors and halide perovskites have shown attractive optoelectronic properties, there are no relevant reports exploring the possibility of integrating antiperovskites and halide perovskites together to form promising heterojunctions.…”