Exploring ferroelectric and magnetic properties of Tb-substituted m = 5 layered Aurivillius phase thin films

Abstract

Here, we report the effect of A-site substitution of Tb at the expense of Bi on the ferroelectric and magnetic properties in m = 5 layered 2-D Aurivillius Bi6Ti3Fe2O18 thin films. The nominal stoichiometry of the prepared compound is Tb0.40Bi5.6Fe2Ti3O18, Tb0.90Bi5.1Fe2Ti3O18, and Bi6Ti3Fe2O18. Phase examination reveals that only 0.40 mol. % is successfully substituted forming Tb0.40Bi5.6Fe2Ti3O18 thin films. Lateral and vertical piezoresponse switching loops up to 200 °C reveal responses for Bi6Ti3Fe2O18, Tb substituted Tb0.40Bi5.6Fe2Ti3O18, and Tb0.90Bi5.1Fe2Ti3O18 thin films along the in-plane (±42.31 pm/V, 88 pm/V and ±134 pm/V, respectively) compared with the out-of-plane (±6.15 pm/V, 19.83 pm/V and ±37.52 pm/V, respectively). The macroscopic in-plane polarization loops reveal in-plane saturation (Ps) and remanence polarization (Pr) for Bi6Ti3Fe2O18 of ±26.16 μC/cm2 and ±22 μC/cm2, whereas, ±32.75 μC/cm2 and ±22.11 μC/cm2, ±40.30 μC/cm2 and ±28.5 μC/cm2 for Tb0.40Bi5.6Fe2Ti3O18 and Tb0.90Bi5.1Fe2Ti3O18 thin films, respectively. No ferromagnetic signatures were observed for Bi6Ti3Fe2O18 and Tb0.40Bi5.6Fe2Ti3O18. However, a weak response was observed for the Tb0.90Bi5.1Fe2Ti3O18 at 2 K. Microstructural analysis of Tb0.90Bi5.1Fe2Ti3O18 revealed that it contains 4 vol. % Fe:Tb rich areas forming FexTbyOz, which accounts for the observed magnetic moment. This study demonstrates the importance of thorough microstructural analysis when determining whether magnetic signatures can be reliably assigned to the single-phase system. We conclude that Tb0.40Bi5.6Fe2Ti3O18 and Tb0.90Bi5.1Fe2Ti3O18 samples are not multiferroic but demonstrate the potential for Fe-RAM applications.

Charged Domain Wall and Polar Vortex Topologiesin a Room Temperature Magnetoelectric Multiferroic Thin Film

“…One ferroelectric block with one dielectric layer corresponds to half of one (0.5) Aurivillius phase unit cell. The Aurivillius phase materials are established ferroelectrics, strongly favouring in-plane polarisation, with spontaneous electrical polarisation (Ps) of 50 μC cm −2 , [40][41] as observed from previous macroscopic polarisation vs. electric field measurements, piezoresponse force microscopy measurements and ab initio calculations. In this contribution, we use HAADF-STEM cross-sectional imaging to investigate polar behaviour within sections of the B6TFMO films.…”

Robust In‐Plane Ferroelectricity in Ultrathin Epitaxial Aurivillius Films

“…[9,12,13] All this makes them attractive for device applications. Furthermore, the ferroelectric properties in the Aurivillius family are preserved or even enhanced upon doping with magnetic ions, [14][15][16] which is beneficial for obtaining room temperature multiferroicity as well as magnetoelectric coupling effects. [15,[17][18][19][20][21] The ferroelectric performance of ceramic Aurivillius-based capacitors is outstanding [3] , but very little is known about the ferroelectric properties of the technologically relevant thin-film form.…”

Progress and Perspectives on Aurivillius-Type Layered Ferroelectric Oxides in Binary Bi4Ti3O12-BiFeO3 System for Multifunctional Applications

“…Currently, polycrystalline BFTO-n thin films were successfully prepared by typical chemical solution deposition method or sol-gel method [81][82][83][84][85][86][87][88][89][90], which consists of the solution preparation and spin coating processing. The practical substrate usually adopts the Pt/Ti/SiO 2 /Si substrate [81][82][83][84][85][86], fused quartz substrate [90], sapphire substrate [25], and so on. Figure 4d,e shows the field emission scanning electron microscope (FE-SEM) images of surface and fracture morphologies of the BFTO-n thin film.…”

“…The ion substitution would influence the inter-strain and tolerance factor. The A-site can be occupied by large cations such as Na + [20], K + [107], Ca 2+ [108], Sr 2+ [46], Ba 2+ [26], Pb 2+ [109], Y 3+ [21], Bi 3+ and Ln (La [27], Nd [22], Sm [23], Gd [24], Ce [110][111][112],Tb [25], Dy [113], Ho [114], Er [115,116], Eu [56], Yb, Th [117], Pr [118]), the B-site can accommodate hetero-valent elements (Ti 4+ , W 6+ [36], Nb 5+ [43], Ta 5+ [119], V 5+ , Cu 2+ [120], Mo 6+ [121], and Mg 2+ [43]) and a variety of magnetic elements (Fe, Cr, Mn, Co, and Ni) [32][33][34][35][36][37][38][39][40][41][42][43][44]52], which will create the possibility of magnetic ordering. More interestingly, the halogen or nitrogen elements substitution on the O-sites was accomplished [122,123].…”

“…In the last decade, numerous pieces of research focused on the BFTO-n with integer n, for example, Bi 5 FeTi 3 O 15 , Bi 6 Fe 2 Ti 3 O 18 , and Bi 7 Fe 3 Ti 3 O 21 . The reported studies have mainly embodied two aspects: (i) doping ions into A-sites [19][20][21][22][23][24][25][26][27][28][29] and/or substituting magnetic transition ions into B-sites [30][31][32][33][34][35][36][37][38][39][40][41][42][43] inside the layered perovskite structure to realize a significant enhancement in the multiferroic performances, and (ii) controllable synthesis of materials in ceramics [44][45][46], thin films [47][48][49][50][51][52], nano-crystallines [53][54][55][56][57][58] and single crystals [59][60][61] to observe the growth process [62][63][64]…”