Author
D.A. Landínez Téllez
Other affiliations: Federal University of Pernambuco
Bio: D.A. Landínez Téllez is an academic researcher from National University of Colombia. The author has contributed to research in topics: Rietveld refinement & Magnetization. The author has an hindex of 14, co-authored 131 publications receiving 673 citations. Previous affiliations of D.A. Landínez Téllez include Federal University of Pernambuco.
Papers published on a yearly basis
Papers
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TL;DR: In this article, the authors reported on LAPW ab initio calculations within the generalized gradient approximation (GGA) to density functional theory (DFT) for another double perovskite, namely, Sr2CrMoO6.
Abstract: Complex perovskite materials with the A2BB′O6 formula have been recently studied because of their peculiar magnetic and electronic properties. The origin of magnetism in the double perovskite Sr2FeMoO6 brought these properties again into discussion. Recently, a new interaction mechanism was proposed for cases in which the hybridization of 3d and 2p levels of Mo with the 3d Fe levels is responsible for the half-metallic behavior in the Sr2FeMoO6 material. We report on LAPW ab initio calculations within the generalized gradient approximation (GGA) to density functional theory (DFT) for another double perovskite, namely, Sr2CrMoO6. Our results show that this is also a half-metallic system. We correlate our results with an extension of the recent model proposed by Sarma to explain the conduction mechanism in this compound.
59 citations
TL;DR: In this paper, the synthesis of the YBa 2 Cu 3− x (PO 4 ) x O 7 − δ superconducting material by the standard solid-state reaction is reported.
Abstract: Synthesis of the YBa 2 Cu 3− x (PO 4 ) x O 7– δ superconducting material by the standard solid-state reaction is reported. DC resistivity measurements reveal the improvement of the critical temperature ( T C ) when substitution of phosphate in the Cu sites is performed. A bulk T C =97 K was determined by the criterion of the maximum in the temperature derivative of electrical resistivity. Structure characterization by means the X-ray diffraction technique shows the crystalline appropriated distribution of PO 4 into the CuO 2 superconducting planes. In order to examine the effect of phosphates on the pairing mechanism close to T C , conductivity fluctuation analysis was performed by the method of logarithmic temperature derivative of the conductivity excess. We found the occurrence of Gaussian-like fluctuations. The correlations of the critical exponents with the dimensionality of the fluctuation system for each Gaussian regime were performed by using the Aslamazov–Larkin theory. The Ginzburg number for this superconducting material is predicted and the critical magnetic fields, critical current density and the jump in the specific heat at the critical temperature are theoretically determined.
54 citations
TL;DR: In this paper, the authors reported several ab initio calculations performed for Sr2CoWO6 by means of the density functional theory and the linearized augmented plane wave method for both spin orientations.
27 citations
TL;DR: In this paper, structural analysis, magnetic ordering, ferroelectric behavior and electronic structure of Sr 2 ZrMnO 6 complex perovskite was performed by Rietveld refinement of experimental X-ray diffraction patterns.
23 citations
TL;DR: In this paper, the synthesis and characterization of new Sr2TiMnO6 manganite-like material was reported, which was produced by the solid state reaction method.
23 citations
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16 Mar 1993
TL;DR: Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure as discussed by the authors.
Abstract: Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.
924 citations
TL;DR: A survey of the literature for ca. one thousand B-site substituted perovskite oxides can be found in this article, together with their electronic and magnetic properties and properties.
815 citations
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TL;DR: The electronic structure of the perovskite LaCoO3 for different spin states of Co ions was calculated in the local-density approximation LDA+U approach and shows that Co 3d states of t(2g) symmetry form narrow bands which could easily localize, while e(g) orbitals, due to their strong hybridization with the oxygen 2p states, form a broad sigma* band.
Abstract: The electronic structure of the perovskite LaCoO$_3$ for different spin states of Co ions was calculated in the LDA+U approach. The ground state was found to be a nonmagnetic insulator with Co ions in a low-spin state. Somewhat higher in energy we found two intermediate-spin states followed by a high-spin state at significantly higher energy. The calculation results show that Co 3$d$ states of $t_{2g}$ symmetry form narrow bands which could easily localize whilst $e_g$ orbitals, due to their strong hybridization with the oxygen 2$p$ states, form a broad $\sigma^*$ band. With the increase of temperature which is simulated by the corresponding increase of the lattice parameter, the transition from the low- to intermediate-spin states occurs. This intermediate-spin (occupation $t_{2g}^5e_g^1$) can develop an orbital ordering which can account for the nonmetallic nature of LaCoO$_3$ at 90 K$<$T$<$500 K. Possible explanations of the magnetic behavior and gradual insulating-metal transition are suggested.
531 citations
TL;DR: In this paper, the projection of the eigenfunctions obtained in standard plane-wave first-principle electronic-structure calculations into atomic-orbital basis sets is proposed as a formal and practical link between the methods based on plane waves and the ones based on atomic orbitals.
Abstract: The projection of the eigenfunctions obtained in standard plane-wave first-principle electronic-structure calculations into atomic-orbital basis sets is proposed as a formal and practical link between the methods based on plane waves and the ones based on atomic orbitals. Given a candidate atomic basis, ({\it i}) its quality is evaluated by its projection into the plane-wave eigenfunctions, ({\it ii}) it is optimized by maximizing that projection, ({\it iii}) the associated tight-binding Hamiltonian and energy bands are obtained, and ({\it iv}) population analysis is performed in a natural way. The proposed method replaces the traditional trial-and-error procedures of finding appropriate atomic bases and the fitting of bands to obtain tight-binding Hamiltonians. Test calculations of some zincblende semiconductors are presented.
349 citations
01 Mar 2002
TL;DR: High quality thin films of the ferromagnetic semiconductor EuO have been prepared and were studied using a new form of spin-resolved spectroscopy, finding that large changes in the electronic structure across the Curie and metal-insulator transition temperature are caused by the exchange splitting of the conduction band.
Abstract: High quality thin films of the ferromagnetic semiconductor EuO have been prepared and were studied using a new form of spin-resolved spectroscopy. We observed large changes in the electronic structure across the Curie and metal-insulator transition temperature. We found that these are caused by the exchange splitting of the conduction band in the ferromagnetic state, which is as large as 0.6 eV. We also present strong evidence that the bottom of the conduction band consists mainly of majority spins. This implies that doped charge carriers in EuO are practically fully spin polarized.
165 citations