Microstructure and interface studies ofLaVO3/SrVO3superlattices

Abstract

The structure and interface characteristics of (LaVO3)6m(SrVO3)m superlattices deposited on (100)-SrTiO3 (STO) substrate were studied using Transmission Electron Microscopy (TEM). Crosssection TEM studies revealed that both LaVO3 (LVO) and SrVO3 (SVO) layers are good single crystal quality and epitaxially grown with respect to the substrate. It is evidenced that LVO layers are made of two orientational variants of a distorted perovskite compatible with bulk LaVO3 while SVO layers suffers from a tetragonal distortion due to the substrate induced stain. Electron Energy Loss Spectroscopy (EELS) investigations indicate changes in the fine structure of the V L23 edge, related to a valence change between the LaVO3 and SrVO3 layers.

Engineered spatial inversion symmetry breaking in an oxide heterostructure built from isosymmetric room-temperature magnetically ordered components

“…The red and green functions superimposed on the intensity profile correspond to the crenel and sinewave modulation models used to produce the XRD simulations. The gradual overall decrease in peak height from top to bottom is due to varying cross-section thickness.Low temperature growth of orthorhombic LnFeO 3 films affords domains with the b + tilt both in-and out of plane [47][48][49] .The relative orientation of the in-phase tilt to the A site ordering is critical in determining the presence of polaritywhen the in-phase tilt is aligned with the A site ordering, the symmetry is polar P2 1 ma, whereas alignment of the out-ofphase tilt along this direction affords non-polar P2 1 /m (Figure 3 d). In order to identify the relative orientation of the b + tilt the pole figure of the (111) Figure S9), and thus both non-polar P2 1 /m and polar P2 1 ma structures are formed in an approximate ratio of 5/1 based on diffracted intensities.…”

Designing ferromagnetism in vanadium oxide based superlattices

“…13,15 For superlattices, substrate-induced strain may change the situation in a way which depends on the growth direction. Experiments 12,13 confirm that the growth direction for the experimentally relevant superlattices is [001] (in the ideal cubic perovskite notation) and we focus on this case here. Recent experimental studies of superlattices 12 and of LaVO 3 thin films, which apparently have the same growth direction, 13 suggest that the rotations are of the type a − a + c −17,18 and indicate that the dominant rotation is around the axis defined by the growth direction: α = β ≈ 3 • and γ ≈ 11.5 • .…”

“…For the experimentally studied superlattices, c/a ∼ 1.02. 6,12 The V-O bond lengths have not been determined but, as discussed in more detail in the Appendix, our studies indicate that all V-O bonds have essentially the same length. Further we show that a few percent differences have no significant effect on our study of ferromagnetism.…”

“…12,13 In these structures in-plane rotation along the growth directionẑ = [001] is large γ = c = 11.5 • (presumably because of the strain imposed by the substrate), while the out-of-plane rotation is small (α = β = a = 3 • ) perhaps because the system is free to relax along the growth direction. We concentrate on the effect of the large rotation by fixing the in-plane angles to 3 • while varying the out-of-plane angles over a wide range from 10 • → 18 • .…”

“…In this study, we combine single-site dynamical mean field approximation 11 with realistic band structure calculations including the effects of the octahedral rotations to determine the ferromagnetic-paramagnetic phase diagram in superlattices with the crystal structures believed relevant 12,13 to the experiments of Ref. 6.…”