Highly Tunable Ferroelectricity in Hybrid Improper Ferroelectric Sr₃Sn₂O₇

Abstract

The successful theoretical prediction and experimental demonstration of hybrid improper ferroelectricity (HIF) provides a new pathway to couple octahedral rotations, ferroelectricity, and magnetism in complex materials. To enable technological applications, an HIF with a small coercive field is desirable. Sr 3 Sn 2 O 7 single crystals are successfully grown, and it is discovered that they exhibit the smallest electric coercive field at room temperature among all known HIFs. Furthermore, it is demonstated that a small external stress can repeatedly erase and regenerate ferroelastic domains. In addition, using in-plane piezo-response force microscopy, abundant charged and neutral domain walls are charaterized. The observed small electrical and mechanical coercive field values are in accordance with the results of the first-principles calculations on Sr 3 Sn 2 O 7 , which show low energy barriers for both 90° and 180° polarization switching compared to those in other experimentally demonstrated HIFs. The findings represent an advancement towards the possible technological implemetation of functional HIFs.

Hybrid Improper Ferroelectricity in Highly Cleavable Single Crystals of Dion‐Jacobson‐Compound CsBiNb2O7

“…Recently, a relatively new mechanism leading to ferroelectricity called "hybrid improper ferroelectricity (HIF)" [1,2] has drawn a significant scientific and technological interest, partially because most of those HIF compounds do not contain Pb, so can be candidates for replacing Pb-based ferroelectrics. [3][4][5][6][7][8][9] The key point of HIF is that the hybridization of two or more nonpolar lattice distortions leads to the existence of spontaneous polarization. [10] Compared with normal improper ferroelectricity, each of the two or more lattice distortion modes might be associated with switching the polarization in HIF independently.…”

Enhanced hybrid improper ferroelectricity in Fe/Nb cosubstituted Ca3Mn2O7 ceramics

“…This larger grain size could prevent the pinning effect arising from grain boundary and beneficial to polarization switching. 41 The refinement results reveal that Ca 3 [Mn 1x (Fe 0.5 Nb 0.5 ) x ] 2 O 7 ceramics all adopt the polar A2 1 am phase structure at room temperature, and no Acaa phase is detected (see Figure 5A and Figure 6). Thermal analysis indicates that Curie temperature T c for Ca 3 [Mn 0.5 (Fe 0.5 Nb 0.5 ) 0.5 ] 2 O 7 is approximately 983.5 K (see Figure 7).…”

Multifunctionality of Li2SrNb2O7: Memristivity, Tunable Rectification, Ferroelasticity, and Ferroelectricity

“…The reversible domain manipulation is as shown in Figure S1b–f, Supporting Information. So far, in bilayer perovskite family, only Li 2 SrNb 2 O 7 , Sr 3 Sn 2 O 7 , [ 17 ] and Ca 3 Ru 2 O 7 [ 18 ] reveal the feasibility to tailor the twin patterns through mechanical stimuli at RT. A clear feature at 217 K has been observed in the permittivity ε along a and c axes as a function of temperature (Figure 1d).…”

“…[15,16] Therefore, searching for new FE ionic conductor materials with good intrinsic performance is highly desirable, and it will provide a great opportunity for anomalous electronic behaviors and multifunctional device applications.The n = 2 Ruddlesden-Popper (R-P) phase bilayer perovskite family holds structural low dimensionality that is favored for enhanced ionic conduction. Moreover, it is also an excellent playground of multifunctionality, in which the various oxygen octahedron displacement modes create rich structural orderings such as ferroelasticity, [17,18] hybrid improper ferroelectricity, [19,20] and topological vortices in real space. [21][22][23] So far, (doped) Li 2 SrNb(Ta) 2 O 7 is the only reported Li-containing system in this family, thus the most promising candidate for ionic conductors.…”