149Sm and 57Fe nuclear resonant inelastic scattering of filled skutterudites SmFe4X12 (X: pnictogen)

Abstract

149 Sm and 57 Fe nuclear resonant inelastic scattering (NRIS) measurements were carried out on SmFe 4 P 12 , SmFe 4 As 12 and SmFe 4 Sb 12 . A clear dip structure of the 57 Fe NRIS spectrum was found in SmFe 4 P 12 , which was not clearly observed for SmFe 4 As 12 and SmFe 4 Sb 12 . On the other hand, the line width of the phonon excitation in the 149 Sm NRIS spectrum increases with increasing the ionic radius of the pnictogen. These findings imply that the hybridization between the Sm and Fe phonon modes is correlated to changes in the ionic radius of the pnictogen.

Atomic dynamics of low-lying rare-earth guest modes in heavy fermion filled skutteruditesROs4Sb12(Tsutsui1, Uchiyama2, Sutter3 et al. 2012Phys. Rev. BSelf Cite262100View full textAdd to dashboardCite

“…9 Many investigations were carried out by both macroscopic and microscopic measurements. For the filled skutterudites, observations of low-lying dispersionless modes below ∼10 meV in inelastic neutron and x-ray scattering experiments [10][11][12][13][14][15][16][17] and those of Einstein temperatures below ∼100 K in specific heat, x-ray diffraction, extended x-ray absorption fine structure (EXAFS), and nuclear magnetic resonance (NMR)/nuclear quadrupole 13 44 resonance (NQR) experiments have been reported. [18][19][20][21][22][23][24][25] At the beginning of the investigation of low-lying optical modes in filled skutterudites, 6,10,12,[26][27][28] which are called guest modes hereafter, it was discussed whether or not the guest modes were localized.…”

A comparison of the local structure in ball-milled and hand ground skutterudite samples using EXAFS

“…Our earlier value of q E for the CeeP pair [18] in CeFe 4 P 12 was 148 K, reasonably consistent with these values. Because of the significantly smaller lattice parameters, q E is expected to be highest for the phosphides, and in systematic nuclear resonance inelastic scattering studies of the skutterudites SmFe 4 X 12 , X ¼ P, As, Sb, [21] the phonon mode is indeed highest for SmFe 4 P 12 (126 K). Thus it is not clear why the values of Nitta et al are so high for antimonides.…”

Complex vibrations in arsenide skutterudites and oxyskutterudites

“…First, some measurements and corresponding calculations focus more on the mode energies, and for low dispersion modes a peak can be observed. Examples include inelastic neutron scattering for La(Ce)Fe 4 Sb 12 25 where adding a rattler introduces a low dispersion mode, and nuclear resonant inelastic scattering 26 which shows well defined peaks corresponding to low dispersing phonon modes. However these modes are the collective motion of several atoms and in general do not probe the atoms involved directly, although in some cases one atom may dominate the response.…”