In: Journal of Physics: Condensed Matter, 2017, vol. 29, no. 49, p. 495601
We studied the structural, magnetic and electronic properties of ${\rm SrFeO}_{3- \delta}$ (SFO) thin films and ${\rm SrFeO}_{3-\delta}$ /${\rm La}_{2/3}$ ${\rm Ca}_{1/3}$ MnO3 (LCMO) superlattices that have been grown with pulsed laser deposition (PLD) on ${\rm La}_{0.3}$ ${\rm Sr}_{0.7}$ ${\rm Al}_{0.65}$ ${\rm Ta}_{0.35}$ ${\rm O}_{3}$ (LSAT) substrates. X-ray reflectometry and scanning ...
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In: Physical Review B, 2017, vol. 96, no. 4, p. 041204
Elucidating the details of electron-phonon coupling in semiconductors and insulators is a topic of pivotal interest, as it governs the transport mechanisms and is responsible for various phenomena such as spectral-weight transfers to phonon sidebands and self-trapping. Here, we investigate the influence of the electron-phonon interaction on the excitonic peaks of rutile TiO2, revealing a strong...
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In: Physical Review B, 2017, vol. 95, no. 19, p. 195107
With infrared (IR) ellipsometry and dc resistance measurements, we investigated the photodoping at the (001) and (110) surfaces of SrTiO3 (STO) single crystals and at the corresponding interfaces of LaAlO3/SrTiO3 (LAO/STO) heterostructures. In the bare STO crystals, we find that the photogenerated charge carriers, which accumulate near the (001) surface, have a similar depth profile and sheet...
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In: Nature Communications, 2017, vol. 8, no. 1, p. 13
Anatase TiO₂ is among the most studied materials for light-energy conversion applications, but the nature of its fundamental charge excitations is still unknown. Yet it is crucial to establish whether light absorption creates uncorrelated electron–hole pairs or bound excitons and, in the latter case, to determine their character. Here, by combining steady-state angle-resolved...
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In: Physical Review B, 2017, vol. 95, no. 5, p. 054512
Using muon spin rotation and infrared spectroscopy, we study the relation between magnetism and superconductivity in Ba1−xKxFe2As2 single crystals from the underdoped to the slightly overdoped regime. We find that the Fe magnetic moment is only moderately suppressed in most of the underdoped region where it decreases more slowly than the Néel temperature TN. This applies for both the total...
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In: Physical Review B, 2017, vol. 95, no. 2, p. 024105
With infrared (IR) and terahertz (THz) ellipsometry we investigated the anisotropy of the IR-active phonon modes in ${\mathrm{SrTiO}}_{3}$ (110) single crystals in the tetragonal state below the so-called antiferrodistortive transition at T∗=105 K. In particular, we show that the anisotropy of the oscillator strength of the so-called R mode, which becomes weakly IR active below T∗, is a...
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In: Applied Physics Letters, 2016, vol. 108, no. 5, p. 052901
We present a combined study with time-domain terahertz and conventional far-infrared ellipsometry of the temperature dependent optical response of SrTiO₃thin films (82 and 8.5 nm) that are grown by pulsed-laser deposition on (La0.3Sr0.7) (Al0.65Ta0.35)O₃ (LSAT) substrates. We demonstrate that terahertz ellipsometry is very sensitive to the optical...
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In: EPL (Europhysics Letters), 2016, vol. 113, no. 4, p. 47005
With infrared ellipsometry we studied the response of the confined electrons in γ-Al₂O₃/SrTiO₃ (GAO/STO) heterostructures in which they originate predominantly from oxygen vacancies. From the analysis of a so-called Berreman mode, that develops near the highest longitudinal optical phonon mode of SrTiO₃, we derive the sheet carrier density, N s , the...
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