Search results for "Laser deposition"
showing 10 items of 80 documents
Study of the bandgap renormalization in Ga-doped ZnO films by means of optical absorption under high pressure and photoelectron spectroscopy
2008
Abstract In this paper we investigate the band gap renormalization in heavily Ga-doped ZnO thin films deposited by pulsed laser deposition on C -plane sapphire and mica substrates. Thin films were studied by ultraviolet photoelectron spectroscopy and also by optical measurements under high pressure. The Fermi-level shift, as obtained from ultraviolet photoelectron experiments, exhibits a relatively small and positive shift (about 0.3 eV) with respect to the valence band for increasing electron concentrations up to 1021 cm−3. The optical gap exhibits a much larger increase (0.6 eV) for the same concentration range. Absorption measurements under pressure show that the pressure coefficient of …
Pulsed laser deposition of Sr2FeMoO6 thin films
2005
Abstract The effect of various deposition conditions and after-growth protocols on the magnetic and transport properties of Sr 2 FeMoO 6 films has been explored. It is found that the saturation magnetization and the magnetoresistance (MR) are dominated by the degree of cationic order, and the strain effects are clearly evidenced in a lower T C . The after-growth annealing of the films and the deposition of a buffer layer has been found to relax the film strains. This translates into a clear increase of the measured low-field magnetoresistance ratios.
Cationic vacancies and anomalous spectral-weight transfer in Ti1−xTaxO2thin films studied via polarization-dependent near-edge x-ray absorption fine …
2013
We report the electronic structures of Ta-doped anatase TiO 2 thin films grown by pulsed laser deposition (PLD) with varying magnetization using a combination of first-principles calculations and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The roles of Ta doping and Ti vacancies are clarified, and the observed room-temperature ferromagnetism is attributed to the localized magnetic moments at Ti vacancy sites ferromagnetically ordered by electron charge carriers. O K -edge spectra exhibit significant polarization dependence which is discussed and supported by first-principles calculations in relation to both the crystal symmetry and the formation of defects. In particula…
Local structure and magnetization of ferromagnetic Cu-doped ZnO films: No magnetism at the dopant?
2016
Abstract Relationship between magnetism and structure of Cu-doped ZnO was investigated at macroscopic and microscopic levels. Thin Zn1−xCuxO films (x = 0.02, 0.04, 0.07 and 0.10) were prepared by a pulsed laser deposition and characterized via superconducting quantum interference device (SQUID) magnetometry, high-resolution x-ray diffraction, and Cu K-edge and Zn K-edge x-ray absorption, x-ray linear dichroism and x-ray circular magnetic dichroism spectroscopy. Even though the samples exhibit room-temperature ferromagnetism with magnetization that increases with Cu concentration, we did not detect signatures of local magnetic moments associated with Cu atoms, as evidenced by the lack of any…
Epitaxial Films of Relaxor Ferroelectric PbMg1/3Nb2/3O3in Strong Electric Fields
2005
Epitaxial thin films of perovskite relaxor ferroelectric PbMg 1/3 Nb 2/3 O 3 were grown on MgO (001) substrates by pulsed laser deposition using La 0.5 Sr 0.5 CoO 3 bottom electrode layers. Dielectric response of the films was experimentally studied as a function of temperature and frequency in a broad range of amplitudes of ac electric field (to 10 MV/m) and magnitudes of dc electric field (to 50 MV/m). At small fields, a glass-like behavior was observed. With increasing magnitude of the dc field, an onset of a polar state was detected. The orientation of the polar clusters along the direction of the field and fluctuations of the direction of their dipole moments were suggested to determin…
Electrical detection of the spin reorientation transition in antiferromagnetic TmFeO3 thin films by spin Hall magnetoresistance
2021
$\mathrm{Tm}\mathrm{Fe}{\mathrm{O}}_{3}$ (TFO) is a canted antiferromagnet that undergoes a spin reorientation transition (SRT) with temperature between 82 and 94 K in single crystals. In this temperature region, the N\'eel vector continuously rotates from the crystallographic $c$ axis (below 82 K) to the $a$ axis (above 94 K). The SRT allows for a temperature control of distinct antiferromagnetic states without the need for a magnetic field, making it apt for applications working at terahertz frequencies. For device applications, thin films of TFO are required as well as an electrical technique for read-out of the magnetic state. Here, we demonstrate that orthorhombic TFO thin films can be…
Structural characterization and anomalous Hall effect of Rh2MnGe thin films
2015
Abstract We present the preparation, structural investigations, and transport properties of L21-ordered epitaxial Rh2MnGe Heusler thin films grown by pulsed laser deposition. The films grow (1 0 0) oriented on (1 0 0)MgO substrate with [ 0 1 1 ] Rh 2 MnGe ∥ [ 0 1 0 ] MgO . The rocking curve widths of (4 0 0) reflections are below 1° and decrease with increasing deposition temperature. The flat surface of the thin films allowed lithographic patterning enabling quantitative magnetotransport measurements. We measured resistivity and the Hall effect. We suggest skew scattering as the dominant effect in the temperature dependent anomalous Hall effect, consistent with the theoretically expected s…
Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization
2014
Yttrium iron garnet (YIG, Y [subscript 3]Fe[subscript 5]O[subscript 12]) films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd[subscript 3]Ga[subscript 5]O[subscript 12]) substrates with (100) orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe), near-bulk room temperature saturation moments (∼135 emu cm[superscript −3]), in-plane easy axis, and damping parameters as low as 2.2 × 10[superscript −4]. These high quality YIG thin films are useful in the investigation…
Optical, X-ray absorption and photoelectron spectroscopy investigation of the Co site configuration in Zn1−xCoxO films prepared by pulsed laser depos…
2007
Abstract In this paper, we investigate the Co site configuration in Zn1−xCoxO thin films by means of different spectroscopic techniques. Thin films were prepared by pulsed laser deposition with Co proportion from 1% to 30%. The Co 2p doublet observed in the X-ray photoelectron spectra exhibits the spin–orbit splitting and shake-up satellites typical of Co+2 ionization states. X-ray absorption spectra at the Co K-edge, taken in fluorescence mode, unambiguously show that Co atoms are in tetrahedral configuration substituting for Zn over the whole composition range. Optical absorption spectra provide further evidence of the tetrahedral coordination of Co cations, both through the internal tran…
Normal Metal-Insulator-Superconductor Tunnel Junctions With Pulsed Laser Deposited Titanium Nitride as Superconductor
2021
Here we report the fabrication of normal metal – insulator – superconductor (NIS) tunnel junctions using superconducting titanium nitride grown by pulsed laser deposition (PLD). The films for NIS junction fabrication were deposited on two different substrates: silicon nitride film and magnesium oxide. TiN films were characterized by means of electrical transport measurements, and films with superconducting transition temperatures above the liquid helium boiling point were chosen for fabrication of NIS junctions. Tunnel junction devices were successfully fabricated using electron beam lithography and shadow evaporation techniques. The insulator layer formation was performed using two differe…