PAC study of the dynamic hyperfine interactions at 111In-doped Sc2O3 semiconductor and comparison with ab initio calculations

E. L. MUÑOZ, D. RICHARD, A. W. CARBONARI, L. A. ERRICO, AND M. RENTERÍA.

Ginebra

Conferencia; HFI/NQI2010, 15th International Conference on Hyperfine Interactions & 19th International Symposium on Nuclear Quadrupole Interaction; 2010

Executive Committee del 3th HFI/NQI International Conference

* Invited talk*The combined experimental and theoretical approach based on electric-field gradient(EFG) determinations by means of hyperfine interaction measurements and ab initiopredictions at impurity atoms has been shown to be a powerful tool to unravelstructural and electronic characterizations of impurities in solids, in particular insemiconductor oxides [1-3]. In this work, PAC experiments using 111In-difussed Sc2O3polycrystals have been performed at the IPEN facility in order to measure theElectric-Field Gradient (EFG) at (111In (EC)-->) 111Cd nuclei located at the cationsite of the semiconductor lattice. The experimental results are compared with abinitio calculations performed with the Full-Potential Augmented Plane Wave plus localorbital (FP-APW+lo) method in the framework of the Density Functional Theory (DFT).The PAC experiments were carried out in the temperature range 10 K – 900 K. The PACspectra obtained in these measurements shows two very well-defined quadrupolefrequencies along the whole temperature range, pointing to the fact that 100% of theprobes are located at both nonequivalent cation sites of the bixbyite structure.Nevertheless, the spectra are dampened at certain intermediate temperatures,indicating the presence of dynamic hyperfine interactions that were analyzed with aperturbation factor based on the Bäverstam and Othaz model [4,5]. The FPAPW+localculations were performed using the Wien2K code. From the ab initio-experimentalcomparison, we can conclude that the Cd impurities localized at the axially symmetricD sites of the crystal structure do not present dynamic interactions while that theCd probes localized at the asymmetric C sites present appreciable dynamicinteractions attributed to the so-called after-effects that follow the electroncapturedecay of the 111In parent isotope of the 111Cd impurity tracer. This scenariocould be supported in terms of the EFG behaviour, predicted by the ab initiocalculations, at Cd impurities as a function of the charge state of the impuritylocated at the different cation sites of the structure.References[1] Anisotropic Relaxations Introduced by Cd Impurities in Rutile TiO2: First-Principles Calculations and Experimental SupportL.A. Errico, G. Fabricius, M. Rentería, P. de la Presa, and M. Forker.Physical Review Letters 89, 55503 (2002).[2] Metal Impurities in an Oxide: Ab Initio Study of Electronic and StructuralProperties of Cd in Rutile TiO2L.A. Errico, G. Fabricius, and M. Rentería.Physical Review B 67, 144104 (2003).[3] Metal Impurities in an Oxide: Ab Initio Study of Electronic and StructuralProperties of Cd in Rutile TiO2G. N. Darriba, L. A. Errico, P. D. Eversheim, G. Fabricius, and M. Rentería.Physical Review B 79, 115213 (2009).[4] U. Bäverstam, R. Othaz, N. De Sousa and B. Ringström, Nucl. Phys. A186, 500(1972).[5] A. Abragam and R. V. Pound, Phys. Rev. 92, 943 (1953).