Effect of partial la filling on the local electronic properties of La xCo4Sb12 studied using 59Co NMR

Chin-Shan Lue, S. M. Huang, C. N. Kuo, F. T. Huang, M. W. Chu

Research output: Contribution to journalArticle

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Abstract

We present a systematic investigation of the LaxCo 4Sb12 skutterudites with x ≤ 0.2 using 59Co nuclear magnetic resonance (NMR) spectroscopy. The NMR line shape, the quadrupole splitting, the Knight shift and the spin-lattice relation rate of each compound have been identified. For LaxCo4Sb 12, the central transition and the quadrupole linewidths increase with the La concentration because of the effect of the inhomogeneous electric field gradient. In addition, each linewidth exhibits a temperature-independent behavior, confirming the non-magnetic characteristic of these materials. The results of the isotropic Knight shift and the spin-lattice relaxation rate provide further information on the electronic structure around the Fermi surfaces of these compounds. In La0.1Co4Sb12 and La0.2Co4Sb12, the low-temperature NMR relaxation rates follow the Korringa behavior, indicating a finite density of carriers at the Fermi level. The high-temperature relaxation rates go over to a semiconductor-like activated form, being consistent with a semimetallic response. A detailed analysis of the spin-lattice relaxation rate established that the partial Co 3d Fermi-level density of states (DOS) increases with the La content. The NMR observations were interpreted in terms of a two-band scenario that consists of predominant d-electron features at low temperatures and exotic behavior of s-character electrons at high temperatures. Moreover, the obtained Fermi-level DOS show good agreement with those observed from the electrical conductivity and the Seebeck coefficient measurements in these La-filled skutterudites.

Original languageEnglish
Article number083029
JournalNew Journal of Physics
Volume10
DOIs
Publication statusPublished - 2008 Aug 20

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nuclear magnetic resonance
electronics
spin-lattice relaxation
quadrupoles
magnetic resonance spectroscopy
Seebeck effect
resonance lines
Fermi surfaces
line shape
electrons
electronic structure
gradients
electrical resistivity
electric fields
temperature

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

@article{3084aaadb4a4429faeb311309bc56306,
title = "Effect of partial la filling on the local electronic properties of La xCo4Sb12 studied using 59Co NMR",
abstract = "We present a systematic investigation of the LaxCo 4Sb12 skutterudites with x ≤ 0.2 using 59Co nuclear magnetic resonance (NMR) spectroscopy. The NMR line shape, the quadrupole splitting, the Knight shift and the spin-lattice relation rate of each compound have been identified. For LaxCo4Sb 12, the central transition and the quadrupole linewidths increase with the La concentration because of the effect of the inhomogeneous electric field gradient. In addition, each linewidth exhibits a temperature-independent behavior, confirming the non-magnetic characteristic of these materials. The results of the isotropic Knight shift and the spin-lattice relaxation rate provide further information on the electronic structure around the Fermi surfaces of these compounds. In La0.1Co4Sb12 and La0.2Co4Sb12, the low-temperature NMR relaxation rates follow the Korringa behavior, indicating a finite density of carriers at the Fermi level. The high-temperature relaxation rates go over to a semiconductor-like activated form, being consistent with a semimetallic response. A detailed analysis of the spin-lattice relaxation rate established that the partial Co 3d Fermi-level density of states (DOS) increases with the La content. The NMR observations were interpreted in terms of a two-band scenario that consists of predominant d-electron features at low temperatures and exotic behavior of s-character electrons at high temperatures. Moreover, the obtained Fermi-level DOS show good agreement with those observed from the electrical conductivity and the Seebeck coefficient measurements in these La-filled skutterudites.",
author = "Chin-Shan Lue and Huang, {S. M.} and Kuo, {C. N.} and Huang, {F. T.} and Chu, {M. W.}",
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Effect of partial la filling on the local electronic properties of La xCo4Sb12 studied using 59Co NMR. / Lue, Chin-Shan; Huang, S. M.; Kuo, C. N.; Huang, F. T.; Chu, M. W.

In: New Journal of Physics, Vol. 10, 083029, 20.08.2008.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of partial la filling on the local electronic properties of La xCo4Sb12 studied using 59Co NMR

AU - Lue, Chin-Shan

AU - Huang, S. M.

AU - Kuo, C. N.

AU - Huang, F. T.

AU - Chu, M. W.

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N2 - We present a systematic investigation of the LaxCo 4Sb12 skutterudites with x ≤ 0.2 using 59Co nuclear magnetic resonance (NMR) spectroscopy. The NMR line shape, the quadrupole splitting, the Knight shift and the spin-lattice relation rate of each compound have been identified. For LaxCo4Sb 12, the central transition and the quadrupole linewidths increase with the La concentration because of the effect of the inhomogeneous electric field gradient. In addition, each linewidth exhibits a temperature-independent behavior, confirming the non-magnetic characteristic of these materials. The results of the isotropic Knight shift and the spin-lattice relaxation rate provide further information on the electronic structure around the Fermi surfaces of these compounds. In La0.1Co4Sb12 and La0.2Co4Sb12, the low-temperature NMR relaxation rates follow the Korringa behavior, indicating a finite density of carriers at the Fermi level. The high-temperature relaxation rates go over to a semiconductor-like activated form, being consistent with a semimetallic response. A detailed analysis of the spin-lattice relaxation rate established that the partial Co 3d Fermi-level density of states (DOS) increases with the La content. The NMR observations were interpreted in terms of a two-band scenario that consists of predominant d-electron features at low temperatures and exotic behavior of s-character electrons at high temperatures. Moreover, the obtained Fermi-level DOS show good agreement with those observed from the electrical conductivity and the Seebeck coefficient measurements in these La-filled skutterudites.

AB - We present a systematic investigation of the LaxCo 4Sb12 skutterudites with x ≤ 0.2 using 59Co nuclear magnetic resonance (NMR) spectroscopy. The NMR line shape, the quadrupole splitting, the Knight shift and the spin-lattice relation rate of each compound have been identified. For LaxCo4Sb 12, the central transition and the quadrupole linewidths increase with the La concentration because of the effect of the inhomogeneous electric field gradient. In addition, each linewidth exhibits a temperature-independent behavior, confirming the non-magnetic characteristic of these materials. The results of the isotropic Knight shift and the spin-lattice relaxation rate provide further information on the electronic structure around the Fermi surfaces of these compounds. In La0.1Co4Sb12 and La0.2Co4Sb12, the low-temperature NMR relaxation rates follow the Korringa behavior, indicating a finite density of carriers at the Fermi level. The high-temperature relaxation rates go over to a semiconductor-like activated form, being consistent with a semimetallic response. A detailed analysis of the spin-lattice relaxation rate established that the partial Co 3d Fermi-level density of states (DOS) increases with the La content. The NMR observations were interpreted in terms of a two-band scenario that consists of predominant d-electron features at low temperatures and exotic behavior of s-character electrons at high temperatures. Moreover, the obtained Fermi-level DOS show good agreement with those observed from the electrical conductivity and the Seebeck coefficient measurements in these La-filled skutterudites.

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