INVESTIGADORES
ALONSO Roberto Emilio
artículos
Título:
Electric field gradients of CeMIn5 (M = Co, Rh, Ir) heavy-fermion systems studied by perturbed angular correlations and ab initio electronic structure calculations
Autor/es:
M. FORKER; P.R.J. SILVA; J.T.P.D. CAVALCANTE; F.H.M CAVALCANTE; S.M. RAMOS; H. SAITOVICH; E. BAGGIO-SAITOVICH; R. E. ALONSO; M. TAYLOR; L. ERRICO
Revista:
PHYSICAL REVIEW B
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 2013 vol. 87 p. 1151321 - 11513211
ISSN:
1098-0121
Resumen:
The electric field gradient (EFG) at the highly dilute nuclear probe 111Cd in the heavy fermion systems CeMIn5,
M = Co, Rh, and Ir and YCoIn5 has been investigated by perturbed angular correlation (PAC) measurements of
the nuclear electric quadrupole interaction (QI) of 111Cd on In sites. Pure and Sn-doped single crystals prepared
by In-flux synthesis and polycrystalline samples prepared by arc melting have been studied. The samples were
doped with the PAC probe 111Cd by diffusion of the mother isotope 111In. In all samples, several fractions of 111Cd
probe nuclei subject to different QIs have been observed, among them a large fraction of 111Cd in unreacted In
metal. Detailed calculations of the EFG at In nuclei and at Cd probes on In sites of pure and Sn-doped CeMIn5
were preformed, using the full-potential augmented plane wave+local orbital (APW+lo) formalism and taking
into account different variables such as the electronic structure of the hyperfine probes, probe induced structural
distortions, and impurity doping. The excellent agreement between the predicted EFGs and the experimental
results allows us to assign two of the observed EFG components to the lattice sites 1c and 4i of the CeMIn5
compounds and to explain the pronounced difference of the EFG at In and Cd probes on the same lattice position.
Structural distortions induced by the Cd probe and Sn-doping were found to have little effect on the EFG at the Cd
probes. We also show that the local spin density approximation (LSDA) and LDA+U calculations predict very
similar equilibrium structures and EFGs at the In/Cd sites. The extension of the experiments and the calculations
from CeMIn5 to YCoIn5 and LaCoIn5 have established that the influence of the 4f electrons on the EFGs at
impurity sites is negligibly small.