Antiferroelectric-to-ferroelectric phase transition in hexagonal rare-earth iron oxides

Abstract

Ferroic oxides often exhibit exotic behavior, accompanied by phase transitions. Hexagonal rare-earth iron oxides (h-RFeO3), a promising multiferroic system, were reported to exhibit ferroelectricity (FE) when the lattice parameter ratio...

Ferroelectric and Magnetic Properties of Hexagonal ErFeO3 Epitaxial Films

“…The antiferroelectric-to-ferroelectric transition by increasing E max is a consequence of an increase in the migration length of the domain wall. 26 Similar transitions were observed in the h-RMnO 3 films, with R having a larger Z (R = Tb, Dy). 20,21 The P r and coercive electric field (E c ) values of the film were 2.1 μC/cm 2 and 0.15 MV/cm, respectively.…”

“…Conversely, at E max = 1.4 MV/cm (Figure b), the P – E curve of the h-ErFeO 3 film showed a clear single ferroelectric hysteresis loop, indicating the ferroelectric behavior of the film at high E max regions. The antiferroelectric-to-ferroelectric transition by increasing E max is a consequence of an increase in the migration length of the domain wall . Similar transitions were observed in the h-RMnO 3 films, with R having a larger Z (R = Tb, Dy). , The P r and coercive electric field ( E c ) values of the film were 2.1 μC/cm 2 and 0.15 MV/cm, respectively.…”

“…Hexagonal rare-earth manganese (iron) oxide (h-RMn­(Fe)­O 3 ) is a typical multiferroic material with geometric ferroelectricity. , Its ferroelectric polarization arises from the geometric tilting of Mn­(Fe)­O 5 bipyramids and the corresponding displacement of R ions . The three ferroelectric features in the h-RMn­(Fe)­O 3 system include the high ferroelectric transition temperature (e.g., 920 K for h-YMnO 3 ); the ferroelectric domain walls strongly coupled with the magnetic domain walls, causing magnetoelectric properties; ,, and the ferroelectric properties controllable by changing R because the tilting of the Mn­(Fe)­O 5 bipyramids originates from the size difference between R and Mn­(Fe). ,− In the case of h-RFeO 3 , the ferroelectric phase was reported for R = Tm, Yb, and Lu (atomic number Z = 69–71), ,, whereas the antiferroelectric behavior was observed for R = Dy ( Z = 66). , However, the studies on the phase boundary are limited; particularly, the properties of h-RFeO 3 with R = Ho, Er ( Z = 67, 68) are still unclear, although they are located at intermediate regions between the ferroelectric and antiferroelectric h-RFeO 3 . Therefore, we focused on the ferroelectric properties of h-RFeO 3 with R = Er ( Z = 68).…”

“…15,19−22 In the case of h-RFeO 3 , the ferroelectric phase was reported for R = Tm, Yb, and Lu (atomic number Z = 69− 71), 18,23,24 whereas the antiferroelectric behavior was observed for R = Dy (Z = 66). 25,26 However, the studies on the phase boundary are limited; particularly, the properties of h-RFeO 3 with R = Ho, Er (Z = 67, 68) are still unclear, although they are located at intermediate regions between the ferroelectric and antiferroelectric h-RFeO 3 . Therefore, we focused on the ferroelectric properties of h-RFeO 3 with R = Er (Z = 68).…”

Hexagonal RFeO3 (R = Dy, Er, and Lu) Films Grown on Glass Substrates with Both Magnetic and Ferroelectric Orders

“…h-R FeO 3 nanoparticles can be synthesized by wet-chemical or supercooling methods, although it is difficult to characterize the ferroic properties owing to the existence of impurity phases and their small size. − A more effective method is the epitaxial thin-film growth on single-crystal substrates, such as YSZ(111) and Al 2 O 3 (0001) substrates. A series of h-R FeO 3 ( R = Sc, Y, and Gd–Lu) epitaxial films have been fabricated without impurity phases. − It is suggested that the metastable h-R FeO 3 phase is stabilized owing to the lattice match between the film and single-crystal substrate. Compared to single-crystal substrates, glass substrates are more cost-effective, which is important for future applications.…”