First-principles study of the lattice dynamical properties of strontium ruthenate

Abstract

By means of first-principles calculations, various properties of SrRuO3 are investigated, focusing on its lattice dynamical properties. Despite having a Goldschmidt tolerance factor very close to 1, the phonon dispersion curves of the high-temperature cubic phase of SrRuO3 show strong antiferrodistortive instabilities. The energetics of metastable phases with different tilt patterns are discussed, concluding that the coupling of oxygen rotation modes with anti-polar Sr motion plays a key role in stabilizing the Pnma phase with respect to alternative rotation patterns. Our systematic analysis confirms previous expectations and contributes to rationalizing better why many ABO3 perovskites, including metallic compounds, exhibit an orthorhombic ground state. The zone-center phonon modes of the Pnma phase have been computed, from which we propose partial reassignment of available experimental data. The full dispersion curves have also been obtained, constituting benchmark results for the interpretation of future measurements and providing access to thermodynamical properties.

Energetics of oxygen-octahedra rotations in perovskite oxides from first principles

“…43 For SrRuO 3 and LaNiO 3 , we do not use any Hubbard-U correction, and consider a trivial ferromagnetic spin arrangement as starting point of our simulations; for SrRuO 3 this yields the magnetic solution that has been obtained in previous DFT investigations of this compound, and basically coincides with the experimental state; 63 for LaNiO 3 our simulations yield a non-magnetic configuration, thus reproducing previous calculations and agreeing well with the experimental result. 64,65 Nevertheless, one should keep in mind that the adecuacy of a simple DFT treatment is questionable for such challenging compunds and, hence, our quantitative results for SrRuO 3 and LaNiO 3 should be regarded with some caution.…”

“…1, have been found to play an important role in stabilizing the a − a − c + structure over competing polymorphs in some compounds. 52,62,63 In this Section we discuss how such modes can be treated, and their effect quantified and analyzed, within our present scheme.…”

Electric Field Control of Jahn-Teller Distortions in Bulk Perovskites

“…ABO 3 perovskites often exhibit a nonpolar Pbnm ground state, resulting in a combination of three AFD motions (a − a − c þ pattern of rotations of the oxygen octahedra in Glazer's notation [22]). In this symmetry, Howard and Carpenter [23] pointed out that a JahnTeller distortion pattern automatically appears, which was later explained in terms of a trilinear coupling with AFD motions [14,24]. As a consequence, a Jahn-Teller distortion is not necessarily electronically driven but can, instead, arise from lattice mode couplings in which case a splitting of the electronic states may develop even in the absence of an electronic instability.…”

First-Principles Study of the Thermoelectric Properties of SrRuO3

“…As previously discussed for instance in Ref. 21, the distortion mainly arises from the combination of in-phase rotations The corresponding magnetic moment is also given in µ B /f.u. These atomic motions are also illustrated in Figure 4.…”

“…13 Theoretically, the thermoelectric properties of SrTiO 3 /SrRuO 3 superlattices have been studied 14 and a metallic non-censtrosymmetric ruthenate double-perovskite oxide SrCaRu 2 O 6 with large thermopower anisotropy has been proposed. 15 Although the electronic, structural, magnetic and lattice dynamical properties of bulk SRO have already been extensively explored theoretically, [16][17][18][19][20][21] to the best of our knowledge, the thermoelectric aspects has not been reported. In spite of the fact that the thermoelectric performances of SRO appear relatively modest and do not make it a very promising candidate for technological applications, it remains a very important magnetic oxide compound.…”