Structural phase transition in epitaxial perovskite films

He, Feizhou; Wells, B. O.; Ban, Z.‐G.; Alpay, S. P.; Grenier, Stéphane; Shapiro, S. M.; Si, Weidong; Clark, Anthony C.; Xi, X. X.

doi:10.1103/physrevb.70.235405

Cited by 79 publications

(55 citation statements)

References 37 publications

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“…1 Since this perovskite is chemically stable, exhibits excellent electrical conductivity, and has a good lattice matching with various functional oxides, it is the material of choice for electrodes, heterojunctions, and multiferroic devices. [2][3][4][5][6][7] One of the most important questions concerning the physics of SrRuO 3 is a significance of correlation effects and how physical properties of the material are impacted by correlated movement of electrons. 8 Due to highly extended nature of 4d orbitals, it is natural to assume that correlation effects in 4d transition metal oxides should be weak.…”

Section: Introductionmentioning

confidence: 99%

Ab initioand photoemission study of correlation effects in SrRuO3thin films

et al. 2013

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We present the experimental and theoretical study of correlation effects in epitaxial SrRuO 3 thin films. Experimentally, we have performed resonant ultraviolet photoemission spectroscopy (UPS) and angle-resolved hard x-ray photoemission spectroscopy (HAXPES) measurements. For resonant UPS, the two methods, Fanoprofile fitting of constant initial state spectra and the energy distribution curves equidistant difference spectra, were used to extract Ru 4d partial spectral weight (PSW) in the valence band. We find Ru 4d PSW possessing a clearly pronounced coherent peak at the Fermi level together with angle-resolved HAXPES spectra demonstrating no difference in surface and bulk electronic structure. From comparison of experimental data with theoretical calculations done at density functional theory level, we conclude that SrRuO 3 is a weakly correlated material and electronic structure of it can be consistently described employing first-principles approaches.

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Section: Introductionmentioning

confidence: 99%

Ab initioand photoemission study of correlation effects in SrRuO3thin films

et al. 2013

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“…Fixing of the ͑110͒ favors an orthorhombic phase, while in bulk BiFeO 3 rhombohedral ͗111͘ type polarizations are stable. Recent work on SrTiO 3 thin films [20][21][22] also show that epitaxial strain has significant effects on the structures of thin films. Similar effects have been observed in lead-based relaxors as well, where the near-surface region or "skin" layers have different structures than that of the bulk.…”

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Ground state monoclinic (Mb) phase in (110)c BiFeO3 epitaxial thin films

Viehland

2006

Applied Physics Letters

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The lattice structure of (110)-oriented BiFeO3 epitaxial thin layers has been identified by synchrotron x-ray diffraction. By using (221) and (221¯) peaks in the (HHL) zone, a ground state monoclinic Mb phase has been observed with lattice parameters of (β;am∕√2andcm)=(89.35°;3.985and3.888Å). These results demonstrate a change in phase stability from rhombohedral in bulk single crystals, to monoclinic in epitaxial thin films with two domain states whose polarization is slightly tilted away from [110] towards [111].

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“…Both bulk and films of this material have a metal-insulator transition around 200K. Recent x-ray diffraction measurements on epitaxial films of NdNiO 3 on LaAlO 3 have shown that the out of plane lattice constant exhibits a sudden change at the transition [17]. Further experiments are ongoing to try to determine what makes the two transitions fundamentally different with respect to the clamping effect of the substrate and the relaxation of the overall unit cell dimensions.…”

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“…Clearly the overall rise in T C can be quite large. Further detail will be given in a follow up paper [10], that also includes a discussion of the temperature-strain phase diagram which has been theoretically predicted [11].…”

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Anomalous phase transition in strained SrTiO3 thin films

Wells

Shapiro

et al. 2003

Applied Physics Letters

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We have studied the cubic to tetragonal phase transition in epitaxial SrTiO3 films under various biaxial strain conditions using synchrotron X-ray diffraction. Measuring the superlattice peak associated with TiO6 octahedra rotation in the low temperature tetragonal phase indicates the presence of a phase transition whose critical temperature is a strong function of strain, with TC as much as 50K above the corresponding bulk temperature. Surprisingly, the lattice constants evolve smoothly through the transition with no indication of a phase change. This signals an important change in the nature of the phase transition due to the epitaxy strain and substrate clamping effect. The internal degrees of freedom (TiO6 rotations) have become uncoupled from the overall lattice shape.Perovskite films have received a great deal of interest lately due to the potential for creating working technologies based on a variety of interesting properties such as high-T C superconductivity, colossal magneto-resistivity, ferro-electricity, and variable dielectric constants. These properties can be quite different in thin films versus nominally similar bulk samples. The primary reasons for the changes in properties are believed to be strain and defects. There is also an emerging theoretical effort to treat the effects of strain. To understand the mechanisms for these changes we must be able to conduct detailed microscopic measurements of the atomic and electronic structure.SrTiO 3 (STO) is a nearly ferroelectric material with a large dielectric nonlinearity and low dielectric loss at cryogenic temperature, making it ideal for tunable microwave devices [1]. STO is also a good model system for studying structural phase transitions. Bulk STO crystals are cubic at room temperature, with space group Pm3m(O 1 h ), but become tetragonal, space group I4/mcm(D 18 4h ), below about 105K. This phase transition involves the rotation of TiO 6 octahedra and has been featured historically in the study of structural phase transitions as the classic example of a soft-mode phase transition [2]. The unit cell of the tetragonal phase has a volume four times that of the cubic unit cell, with approximate unit cell of √ 2a× √ 2a×2a, where a is the lattice parameter of cubic unit cell. In this paper we describe the tetragonal phase as pseudo-cubic, in order to compare the structure before and after the phase transition. In this pseudo-cubic frame, the tetragonal phase has additional superlattice peaks at half integer index positions. These superlattice peaks disappear as the temperature is raised through the tetragonal-cubic phase transition. * Present Address: HASYLAB at DESY, Notkestr. 85, 22603 Hamburg, GermanyIn the bulk, the deviation from cubic symmetry is directly related to the rotation angle of the TiO 6 octahedra. This rotation angle has been identified as the order parameter for this phase transition [3]. Correspondingly, the intensities of the superlattice peaks are proportional to the square of the order parameter and can be used to track the phas...

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Structural phase transition in epitaxial perovskite films

Cited by 79 publications

References 37 publications

Ab initioand photoemission study of correlation effects in SrRuO3thin films

Ab initioand photoemission study of correlation effects in SrRuO3thin films

Ground state monoclinic (Mb) phase in (110)c BiFeO3 epitaxial thin films

Anomalous phase transition in strained SrTiO3 thin films

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