Strain tuning of plasma frequency in vanadate, niobate, and molybdate perovskite oxides

Abstract

A novel approach for finding new transparent conductors involves taking advantage of electronic correlations in metallic transition metal oxides, such as SrVO3, to enhance the electronic effective mass and suppress the plasma frequency (ωP ) to infrared. Success of this approach relies on finding a compound with the right electron effective mass and quasiparticle weight Z. Biaxial strain can in principle be a fruitful way to manipulate the electronic properties of materials to tune both of these quantities. In this study, we elucidate the behavior of the electronic properties of early transition metal oxides SrVO3, SrNbO3, and SrMoO3 under strain, using first principles density functional theory and dynamical mean field theory. We show that strain is not an effective way to manipulate the plasma frequency, but dimensionality of the crystal structure and origin of electronic correlations strongly affect the trends in both ωP and Z. arXiv:1907.09860v1 [cond-mat.mtrl-sci]

Cation order control of correlations in double perovskite Sr2VNbO6

“…Earlier DMFT calculations and experiments agree that the parent compounds have mass renormalization factors of Z SrVO3 ∼ 0.5 and Z SrNbO3 ∼ 0.7 [17,[43][44][45]. (This value is very well established for SrVO 3 , but it is harder to verify experimentally in SrNbO 3 due to possible Sr deficiency of the samples.)…”

“…We note that the suitable U values are also implementation dependent: Our values are larger than typical values used for different DFT+DMFT implementations that use a Wannier-based approach rather than a local-projectorbased one. These larger values are explicitly and extensively tested for various (especially 3d) transition metals and are known to capture quantities such as bandwidth renormalization correctly [17,34,35]. The on-site Hund's J value, on the other hand, is not strongly screened and is expected to be very similar in all of these methods.…”

“…Correlated metals can be promising as transparent conductors because of their large carrier concentration compared to doped semiconductors [56]. Both SrVO 3 and SrNbO 3 have been considered as correlated transparent conductors with different transparency windows, where SrVO 3 is transparent on the lower-energy visible spectrum and SrNbO 3 is transparent for blue and ultraviolet light [17,43,56,57]. A natural question to ask at this point is whether the layered l-Sr 2 VNbO 6 double perovskite can bring together the positive aspects of both parent compounds and serve as a transparent metal that is transparent throughout the visible spectrum.…”

“…In this first-principles study, we focus on the seemingly simple double perovskite Sr 2 VNbO 6 . Both parent compounds of Sr 2 VNbO 6 (SrVO 3 and SrNbO 3 ) are metallic perovskites with a single electron in partially filled d shells of their B-site cations (V 4+ and Nb 4+ ) [17]. Using density functional theory + embedded dynamical mean field theory (DFT+DMFT) [18][19][20], we show that this double perovskite has an electronic structure that is strongly intertwined with the cation order and crystal structural parameters (bond-length disproportionation) in an exceedingly sensitive fashion.…”

Cation Order Control of Correlations in Double Perovskite Sr$_2$VNbO$_6$

“…We note that the suitable U values are also implementation dependent: Our values are larger than typical values used for different DFT+DMFT implementations that use a Wannier based approach, rather than a local projector based one. These larger values are explicitly and extensively tested for various, especially 3d, transition metals, and are known to capture quantities such as bandwidth renormalization correctly [17,30,31]. The on-site Hund's J value, on the other hand, is not strongly screened and is expected to be very similar in all of these methods.…”