Magnetodielectric effect and phonon properties of compressively strained EuTiO3 thin films deposited on (001)(LaAlO3)0.29-(SrAl1/2Ta1/2O3)0.71

Kamba, S.; Rushchanskii, K. Z.; Nuzhnyy, D.; Orlita, M.; Lee, J. H.; Hlinka, J.; Lezaic, M.; Dkhil, B.; Bovtun, V.; Goian, V.; Birol, T.; Fennie, C. J.; Gemeiner, P.; Petzelt, J.; Kempa, M.; Schlom, D. G.

doi:10.1103/PhysRevB.85.094435

Journal Article

Magnetodielectric effect and phonon properties of compressively strained EuTiO3 thin films deposited on (001)(LaAlO3)0.29-(SrAl1/2Ta1/2O3)0.71

Kamba, S. ; Goian, V. ; Orlita, M. ; Nuzhnyy, D. ; Lee, J. H. ; Schlom, D. G. ; Rushchanskii, K. Z.FZJ* ; Lezaic, M.FZJ* ; Birol, T. ; Fennie, C. J. ; Gemeiner, P. ; Dkhil, B. ; Bovtun, V. ; Kempa, M. ; Hlinka, J. ; Petzelt, J.

2012
APS College Park, Md.

Physical review / B 85(9), 094435 (2012) [10.1103/PhysRevB.85.094435]

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Please use a persistent id in citations: http://hdl.handle.net/2128/10855 doi:10.1103/PhysRevB.85.094435

Abstract: Compressively strained epitaxial (001) EuTiO3 thin films of tetragonal symmetry have been deposited on (001) (LaAlO3)(0.29)-(SrAl1/2Ta1/2O3)(0.71) (LSAT) substrates by reactive molecular-beam epitaxy. Enhancement of the Neel temperature by 1 K with 0.9% compressive strain was revealed. The polar phonons of the films have been investigated as a function of temperature and magnetic field by means of infrared reflectance spectroscopy. All three in-plane polarized infrared active phonons show strongly stiffened frequencies compared to bulk EuTiO3 in accordance with first-principles calculations. The phonon frequencies exhibit gradual softening on cooling, leading to an increase in static permittivity. Additional polar phonon with frequency near the TO1 soft mode was detected below 150 K. This mode coupled with the TO1 mode was assigned as the optical phonon from the Brillouin zone edge, which is activated in infrared spectra due to an antiferrodistortive phase transition and due to simultaneous presence of polar and/or magnetic nanoclusters. In the antiferromagnetic phase, we have observed a remarkable softening of the lowest-frequency polar phonon under an applied magnetic field, which qualitatively agrees with first-principles calculations. This demonstrates the strong spin-phonon coupling in EuTiO3, which is responsible for the pronounced dependence of its static permittivity on magnetic field in the antiferromagnetic phase.

Keyword(s): J

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Physics, Condensed Matter

Note: This work was supported by the Czech Science Foundation (Projects No. 202/09/0682 and No. P204/12/1163). J.H. Lee and D.G. Schlom were supported by the National Science Foundation through the MRSEC program (Grant No. DMR-1120296). T. Birol and C.J. Fennie were supported by the DOE-BES under Grant No. DE-SCOO02334. Part of this work was supported by the Young Investigators Group Programme of the Helmholtz Association, Germany, Contract No. VH-NG-409. K.Z.R. and M.L. gratefully acknowledge the support of Julich Supercomputing Centre. We are grateful to E. Santava for help with the magnetic measurements.

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