Electronic and structural properties and hyperfine interactions at Sc sites in the semiconductor Sc2O3: TDPAC and ab initio study

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 2010 vol. 82 p. 1 - 9

1098-0121

The time-differential gamma-gamma perturbed-angular-correlation TDPAC technique using 44Ti→44 Sc tracers was applied to study the nuclear quadrupole interaction of the first excited I=1 state of 44 Sc in the cubic bixbyite structure of scandium sesquioxide Sc2O3. In addition, ab initio calculations of electronic and structural properties and hyperfine parameters at the cationic sites of the Sc2O3 structure were performed using the full-potential augmented plane wave plus local-orbital APW+lo method. The accuracy of the calculations and the excellent agreement of the predicted electric-field-gradient  EFG tensors and the structural properties lattice parameters, internal positions with the experimental results enable us to identify the observed hyperfine interactions and to infer the EFG sign that cannot be measured in conventional TDPAC experiments. Additionally, the APW+lo calculations show that the EFG at Sc sites is originated in the population of Sc 3p states and give an explanation for the preferential occupation of the  asymmetric cationic site C of the structure by the 44 Ti doping impurities. Finally, the validity of the ionic model, usually used to describe the EFG at native cation sites, is discussed.