Structural and optical properties of epitaxial CaxBa1-xNb2O6 thin films grown on MgO by pulsed laser deposition (original) (raw)
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Journal of Applied Physics, 2007
Perovskitelike KTa1−xNbxO3 (KTN, x ranging from 0 to 1) thin films were grown on (100)MgO substrates using pulsed laser deposition. X-ray diffraction analyses evidenced the epitaxial growth of the films along the (100) orientation. The optical properties of KTN planar waveguides were characterized by prism coupling for determination of ordinary and extraordinary refractive indices nTE and nTM (transverse electric and transverse magnetic). The influence of Nb content was also investigated relative to the films’ indices. The film behavior and the substrate-to-layer interface were directly qualified from the measured optical data using the experimental and theoretical approach (iWKB) (inverse Wentzel-Kramers-Brillouin). The results showed a change in the refractive index profile at the interface, which may be related to the existence of structural defects.
Crystal Research and Technology, 2003
Calcium barium niobate (CBN), also like strontium barium niobate (SBN), belongs to the materials family of partially filled tetragonal tungsten bronzes, which show relaxor-type ferroelectric phase transitions and large electro-optic effects. For the first time, it was possible to grow large single crystals of Ca 0.25 Ba 0.75 Nb 2 O 6 (CBN-25) and CBN-28 by using different growing techniques. The successful single crystal growth allowed to investigate several physical properties of the novel phase. Herein, we report on measurements of differential thermal analysis (DTA), wavelength dispersion of the refractive indices, temperature dependence of the birefringence and light absorption. Additionally, results of the single crystal X-ray structure analysis are presented.
Pulsed laser deposition of (SrBa)Nb2O6 thin films and their properties
Strontium barium niobate (Sr x Ba 1−x Nb 2 O 6 , shortly SBN) is a solid solution system with tetragonal tungsten bronze crystal structure. It exhibits a ferroelectric phase with only one polar axis and a transition temperature depending on the Sr/Ba ratio. This thesis studies the growth of SBN thin films, in order to obtain a ferroelectric thin film model system for the study of 180 • domain switching close to the ferroelectric phase transition. SBN has been chosen not only because uniaxial, but because it is possible to tune the temperature of phase transition varying the Sr/Ba ratio. It is thus
Evaluation of the Electro-Optic Response of Novel Calcium Barium Niobate Thin Films
2007
The electro-optical coefficient r33 of a novel ferroelectric compound (calcium barium niobate) is estimated using a single beam set-up in a reflection geometry on thin film samples. The quality of the electrode used to apply the exciting field was estimated as a critical parameter. Following an electrode quality optimization we estimated a lower bound for the r33 coefficient as large as 100 pm/V.
2008
In this work, spectroscopic ellipsometry was used to characterise oxide films produced by anodic oxidation of amorphous silicon using an ethylene glycol (0.04 M KNO) solution. The data obtained show that the growth of the oxide is not only a 3 function of the voltage applied, but also of the current density and of the time process. An empiric model based on a power law is proposed for the growth of the oxide using, as parameters, the voltages and the time process. The oxide produced shows porosity of approximately 12%, which can be reduced down to 6% under well-controlled growth conditions.
Growth of Stable Bilayer CrO 2 /MgB 2 Films by Pulsed Laser Deposition
Journal of Superconductivity and Novel Magnetism, 2014
We have used the pulsed laser deposition (PLD) technique followed by post-annealing process with magnesium vapor at 700 • C for 30 min to grow a high-quality CrO 2 /MgB 2 bilayer prepared on Al 2 O 3 (1102) single crystal. The X-ray diffraction patterns showed high-quality orientated growth of MgB 2 phase. The obtained films were approximately 300 nm thick and had lateral dimensions of 5×5 mm 2. SQUID magnetometry, magneto-optical Faraday microscopy, and magneto-transport techniques were used in order to measure the critical current density (J C) that was found to be 7-9 × 10 6 A/cm 2 at 15 K. Transition temperature (T C) for the films was ∼ 37 K. The obtained magnetic hysteresis loops at low temperatures exhibited asymmetry with respect to H = 0. This can be explained in terms of pinning of flux lines in the films due to magnetic interaction with the ferromagnetic CrO 2 layer.