Understanding and Revisiting Properties ofEuTiO3Bulk Material and Films from First Principles

Abstract

Ab initio computations are performed to investigate properties of bulk material and epitaxial films made of EuTiO3 (ETO). A whole family of nanoscale twinned phases, that present complex oxygen octahedra tilting (OOT) and unusual antiferroelectricity, is found to be degenerate in energy with simpler phases (all possessing typical OOT) in bulk ETO. Such degeneracy provides a successful explanation of recently observed anomalous phenomena. The calculations also lead to revisiting the (rich) phase diagram of ETO films.

Complex antipolar2×4×22structure withPnmasymmetry inProsandeev1, Khalyavin2, Raevski3 et al. 2014Phys. Rev. B201120View full textAdd to dashboardCite

“…A polar rotational structure of the "+ + −−" type was studied in first-principles calculations of BiFeO 3 (BFO) [9] under pressure. Polar and nonpolar structures with symmetry different from P nma were discovered in first-principles calculations of EuTiO 3 [10]. The latter two calculations were done for √ 2 × √ 2 × 4 and even longer supercells, along axis c, for example √ 2 × √ 2 × 6, which are consistent with recently found long rotational patterns in NaNbO 3 [11].…”

Elastic and anelastic relaxations associated with phase transitions inEuTiO3

“…It is thus clear that there is coupling between magnetic and structural properties, and hence that EuTiO 3 has the potential to combine ferro/antiferromagnetism, ferroelectricity, and ferroelasticity. As with multiferroic materials in general, a key property relating to individual instabilities and coupling between them is strain, and it is already clear that the imposition of an external strain could lead to a particularly rich phase diagram topology [33][34][35]. This aspect of the intrinsic behavior of EuTiO 3 remains controversial, however, and has not yet been fully characterized for bulk samples.…”

Structural and magnetic phase transitions inEuTi1−xNbxO3

“…In analogy to STO, ETO also undergoes an antiferrodistortive SPT from P m3m to I4/mcm (a 0 a 0 c − in Glazer notation) driven by R-point phonon softening [7]. While the SPT at 105 K in STO has been extensively studied for decades, the transition in ETO was observed only recently [8] but has since attracted much attention in the field and has been the focus of numerous experimental [7,[9][10][11][12][13][14][15] and theoretical [16][17][18] studies.…”