M. Rentería

APPEARANCE OF ROOM-TEMPERATURE FERROMAGNETISM IN CU-DOPED TIO2-DELTA FILMS

In recent years there has been an intense search for room temperature ferromagnetism in doped dilute semiconductors, which have many potentially applications in spintronics and optoelectronics. We report here the unexpected observation of significant room temperature ferromagnetism in a semiconductor doped with nonmagnetic impurities, Cu-doped TiO

Metal impurities in an oxide: Ab initiostudy of electronic and structural properties of Cd in rutileTiO2

_2

Structure of extremely nanosized and confined In-O species in ordered porous materials

thin films grown by Pulsed Laser Deposition. The magnetic moment, calculated from the magnetization curves, resulted surprisingly large, about 1.5

Electric-Field Gradient at Cd Impurities in In2o3. A FLAPW Study

\mu_B

FLAPW Study of the EFG Tensor at Cd Impurities in In2O3

per Cu atom. A large magnetic moment was also obtained from ab initio calculations using the supercell method for TiO

Hyperfine interactions at 181Hf(→181Ta) impurities implanted in Er2O3 and Gd2O3: structural and electronic dependence of the EFG in bixbyite sesquioxides

_2

Impurity Centers in Oxides Investigated by γ-γ Perturbed Angular Correlation Spectroscopy and Ab Initio Calculations

with Cu impurities, but only if an oxygen vacancy in the nearest-neighbour shell of Cu was present. This result suggests that the role of oxygen vacancies is crucial for the appearance of ferromagnetism. The calculations also predict that Cu doping favours the formation of oxygen vacancies.

FP-LAPW Calculations of the EFG at Cd Impurities in Rutile SnO2

In this work we undertake the problem of a transition metal impurity in an oxide. We present an ab initio study of the relaxations introduced in

NON-IONIC CONTRIBUTIONS TO THE ELECTRIC-FIELD GRADIENT AT 111CD/181TA IMPURITIES IN BIXBYITES

{\mathrm{TiO}}_{2}

IMPURITY CATIONIC-SITE POPULATION AND ELECTRIC-FIELD GRADIENT DEPENDENCE ON IONIC SIZE IN BIXBYITES SESQUIOXIDES IMPLANTED WITH 181HF 181TA

when a Cd impurity substitutionally replaces a Ti atom. Using the full-potential linearized-augmented-plane-wave method, we obtain relaxed structures for different charge states of the impurity and computed the electric-field gradients (EFGs) at the Cd site. We find that EFGs, and also relaxations, are dependent on the charge state of the impurity. This dependence is very remarkable in the case of the EFG and is explained by analyzing the electronic structure of the studied system. We predict fairly anisotropic relaxations for the nearest oxygen neighbors of the Cd impurity. The experimental confirmation of this prediction and a brief report of these calculations have recently been presented [Phys. Rev. Lett. 89, 55503 (2002)]. Our results for relaxations and EFGs are in clear contradiction with previous studies of this system that assumed isotropic relaxations, and point out that no simple model is viable to describe relaxations and the EFG at Cd in