title: Infrared phonon spectroscopy of a compressively strained (001) SrTiO₃ film grown on a (110) NdGaO₃ substrate.
abstract: Polarized infrared reflectivity was measured between 5 and 300 K on a 17 nm thick, 1.1% compressively strained epitaxial (001) SrTiO(3) film and the orthorhombic (110) NdGaO(3) substrate upon which it was grown. A strong in-plane infrared anisotropy of the NdGaO(3) substrate was observed and polar modes with B(1u)-and a mixture of B(2u) + B(3u)-symmetry were seen. At low temperatures three new modes arose in the 90-130 cm( - 1) range, which we assigned to 4f Nd electronic transitions. The in-plane SrTiO(3) film phonons showed strong stiffening compared to the phonon frequencies of bulk unstrained SrTiO(3), particularly the soft mode, and the in-plane phonon peaks were found to split. No anomalies were detected as a function of temperature in either the infrared response or lattice parameters of the compressively strained SrTiO(3) film, providing an absence of evidence for the out-of-plane ferroelectric phase transition predicted by theory.
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Praha 8, Czech Republic.
authors.forename: D
authors.initials: D
authors.lastname: Nuzhnyy
authors.forename: J
authors.initials: J
authors.lastname: Petzelt
authors.forename: S
authors.initials: S
authors.lastname: Kamba
authors.forename: X
authors.initials: X
authors.lastname: Martí
authors.forename: T
authors.initials: T
authors.lastname: Cechal
authors.forename: C M
authors.initials: CM
authors.lastname: Brooks
authors.forename: D G
authors.initials: DG
authors.lastname: Schlom