Cubic to Tetragonal Phase Transition of SrTiO3 under Epitaxial Stress: An X-Ray Backscattering Study

Abstract

Employing synchrotron radiation in backscattering geometry we studied the 105 K cubic to tetragonal (CT) phase transition of SrTiO 3 by X-ray diffraction using the (006) reflection of three (001) oriented samples. Two of the crystals were covered with ultra-thin films of YBa 2 Cu 3 O 7Àd (14 nm) and GdBa 2 Cu 3 O 7Àd (28 nm), respectively. We find that the stress induced by the epitaxial layers influences the behavior of the CT transition in two ways. (i) The critical temperature increases by 1.2 K as a result of the homogeneous epitaxial stress (13.5 MPa) introduced into the substrate by the pseudomorphic GdBa 2 Cu 3 O 7Àd film. (ii) Strain affects the critical exponent of the temperature dependence of the order parameter. Furthermore, the microstructure of the tetragonal domains and its temperature dependence are markedly different for the three samples.

Nanostructures on Surface of SrTio<sub>3</sub> Single Crystals Treated by Plasma

“…Selected experimental data concerning to relation of a stoichiometric composition and properties of SrTiO 3 (shortly, STO) single crystals were presented in [8][9][10][11][12][13][14]. Depending on the crystal composition, the cubic crystalline lattice parameter a (space group Pm3m) changes from a = 3.9051 Å in bulk stoichiometric samples to a = 3.9102 Å in oxygen-deficient STO accompanied by a variation of the dielectric constant  r from 360 to 200 and less [7][8][9][10][11][12][13][14].…”

“…Depending on the crystal composition, the cubic crystalline lattice parameter a (space group Pm3m) changes from a = 3.9051 Å in bulk stoichiometric samples to a = 3.9102 Å in oxygen-deficient STO accompanied by a variation of the dielectric constant  r from 360 to 200 and less [7][8][9][10][11][12][13][14].…”

Thermoelectric properties of n-type SrTiO3

“…A k-point mesh of 6 × 6 × 6 was used for total energy calculations and much denser k meshes are used for density of states (17 × 17 × 17), isoenergy surfaces, and transport properties (27 × 27 × 27). We adopted the experimental cubic structure with lattice constant a = 3.906 Å, 50 with the modified Becke-Johnson (mBJ) potential of Tran and Blaha. 51 This potential generally gives improved band gaps for simple semiconductors and insulators.…”

Photoelectron spectroscopy of transition metal oxide interfaces

“…Both materials are cubic perovskites above phase transition temperatures of T ≈ 105 K [32] and T ≈ 800 K [33] for STO and LAO, respectively. At the transition temperature they undergo a second order phase transition to a low temperature tetragonal and rhombohedral phase, respectively, which can both be viewed as slightly distorted cubic structures.…”