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Title: Ferrimagnetism in EuFe{sub 4}Sb{sub 12} due to the Interplay of f-Electron Moments and a Nearly Ferromagnetic Host

Abstract

We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5} edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu{sub 0.95}Fe{sub 4}Sb{sub 12} is a ferrimagnet in which the Fe 3d moment and the Eu{sup 2+} 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L{sub 3} edge XAS, we find that about 13% of the Eu have a formal valence of 3+. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T{sub C} of 85 K in Eu{sub 0.95}Fe{sub 4}Sb{sub 12} to f-electron interaction with the nearly ferromagnetic [Fe{sub 4}Sb{sub 12}]{sup 2.2-} host lattice.

Authors:
; ; ; ;  [1]; ; ; ;  [2];  [1];  [3]
  1. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
  2. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
20951130
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 12; Other Information: DOI: 10.1103/PhysRevLett.98.126403; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; ANTIFERROMAGNETISM; ANTIMONIDES; ELECTRONS; EUROPIUM COMPOUNDS; EUROPIUM IONS; FERRIMAGNETISM; IRON COMPOUNDS; MAGNETIC CIRCULAR DICHROISM; SPIN; TRANSITION TEMPERATURE; X RADIATION; X-RAY SPECTROSCOPY

Citation Formats

Krishnamurthy, V. V., Robertson, J. L., Sales, B. C., Mandrus, D. G., Singh, D. J., Lang, J. C., Haskel, D., Keavney, D. J., Srajer, G., Bilc, D. I., and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996. Ferrimagnetism in EuFe{sub 4}Sb{sub 12} due to the Interplay of f-Electron Moments and a Nearly Ferromagnetic Host. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.126403.
Krishnamurthy, V. V., Robertson, J. L., Sales, B. C., Mandrus, D. G., Singh, D. J., Lang, J. C., Haskel, D., Keavney, D. J., Srajer, G., Bilc, D. I., & Department of Physics, University of Tennessee, Knoxville, Tennessee 37996. Ferrimagnetism in EuFe{sub 4}Sb{sub 12} due to the Interplay of f-Electron Moments and a Nearly Ferromagnetic Host. United States. doi:10.1103/PHYSREVLETT.98.126403.
Krishnamurthy, V. V., Robertson, J. L., Sales, B. C., Mandrus, D. G., Singh, D. J., Lang, J. C., Haskel, D., Keavney, D. J., Srajer, G., Bilc, D. I., and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996. Fri . "Ferrimagnetism in EuFe{sub 4}Sb{sub 12} due to the Interplay of f-Electron Moments and a Nearly Ferromagnetic Host". United States. doi:10.1103/PHYSREVLETT.98.126403.
@article{osti_20951130,
title = {Ferrimagnetism in EuFe{sub 4}Sb{sub 12} due to the Interplay of f-Electron Moments and a Nearly Ferromagnetic Host},
author = {Krishnamurthy, V. V. and Robertson, J. L. and Sales, B. C. and Mandrus, D. G. and Singh, D. J. and Lang, J. C. and Haskel, D. and Keavney, D. J. and Srajer, G. and Bilc, D. I. and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996},
abstractNote = {We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5} edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu{sub 0.95}Fe{sub 4}Sb{sub 12} is a ferrimagnet in which the Fe 3d moment and the Eu{sup 2+} 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L{sub 3} edge XAS, we find that about 13% of the Eu have a formal valence of 3+. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T{sub C} of 85 K in Eu{sub 0.95}Fe{sub 4}Sb{sub 12} to f-electron interaction with the nearly ferromagnetic [Fe{sub 4}Sb{sub 12}]{sup 2.2-} host lattice.},
doi = {10.1103/PHYSREVLETT.98.126403},
journal = {Physical Review Letters},
number = 12,
volume = 98,
place = {United States},
year = {Fri Mar 23 00:00:00 EDT 2007},
month = {Fri Mar 23 00:00:00 EDT 2007}
}
  • We combine x-ray magnetic circular dichroism spectroscopy at Fe L-2,L-3 edges, at Eu M-4,M-5 edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu0.95Fe4Sb12 is a ferrimagnet in which the Fe 3d moment and the Eu2+ 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L-3 edge XAS, we find that about 13% of the Eu have a formal valence of 3+. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T-C of 85 K in Eu0.95Fe4Sb12 to f-electron interaction with the nearly ferromagneticmore » [Fe4Sb12](2.2-) host lattice.« less
  • The Hall resistivity ({rho}{sub xy}), resistivity ({rho}{sub xx}), and magnetization of three metallic ferromagnets are investigated as a function of magnetic field and temperature. The three ferromagnets, EuFe{sub 4}Sb{sub 12} (T{sub c}{approx}84 K), Yb{sub 14}MnSb{sub 11} (T{sub c}{approx}53 K), and Eu{sub 8}Ga{sub 16}Ge{sub 30} (T{sub c}{approx}36 K) are Zintl compounds with carrier concentrations between 1 x 10{sup 21} and 3.5 x 10{sup 21} cm{sup -3}. The relative decrease in {rho}{sub xx} below T{sub c} [{rho}{sub xx}(T{sub c})Y{rho}{sub xx}(2 K)] is 28, 6.5, and 1.3 for EuFe{sub 4}Sb{sub 12}, Yb{sub 14}MnSb{sub 11}, and Eu{sub 8}Ga{sub 16}Ge{sub 30}, respectively. The low carriermore » concentrations coupled with low magnetic anisotropies allow a relatively clean separation between the anomalous ({rho}{sub xy}), and normal contributions to the measured Hall resistivity. For each compound the anomalous contribution in the zero field limit is fit to a{rho}{sub xx}+{sigma}{sub xy}{rho}{sub xx}{sup 2} for temperatures T<T{sub c}. At T=0 the anomalous Hall conductivity {sigma}{sub xy}{sup 0}, is -220 {+-} 5 ({Omega}{sup -1} cm{sup -1}), -14.7 {+-} 1 ({Omega}{sup -1} cm{sup -1}), and 28 {+-} 3 ({Omega}{sup -1} cm{sup -1}) for EuFe{sub 4}Sb{sub 12}, Yb{sub 14}MnSb{sub 11}, and Eu{sub 8}Ga{sub 16}Ge{sub 30}, respectively, and is independent of temperature for T<T{sub c} if the change in spontaneous magnetization (order parameter) with temperature is taken into account. These data are consistent with recent theories of the anomalous Hall effect that suggest that even for stochiometric ferromagnetic crystals, such as those studied in this article, the intrinsic Hall conductivity is finite at T=0, and is a ground state property that can be calculated from the electronic structure.« less
  • Density functional theory (DFT) based calculations of electronic and magnetic properties of filled skutterudites EuFe{sub 4}As{sub 12} have been performed using FP-LAPW method within the framework of the LSDA approach. The rare-earth filled skutterudites have attracted much attention because of the presence of the highly localized f-electrons and d- electrons of rare-earth and transition metal respectively, with high density of states near Fermi level. The calculation performed near the Fermi level of density of states shows the compound to be suitable for thermoelectric application. The exchange-splitting of Eu-4f states were analysed to explain the ferromagnetic behaviour of EuFe{sub 4}As{sub 12}more » with magnetic moment value 5.18 ╬╝{sub B}.« less
  • Rare-earth-filled transition-metal pnictides having the skutterudite-type structure have been proposed for use as high-temperature thermoelectric materials to recover waste heat from vehicle exhaust, among other applications. A previous investigation by this research group of one of the most studied skutterudites, CeFe{sub 4}Sb{sub 12}, found that, when exposed to air, this material oxidized at temperatures that are considerably below the proposed maximum operating temperature. Here, by the combined use of TGA, powder XRD, and XANES, it has been found that the substitution of Ce{sup 3+} and Fe{sup 2+} for larger rare-earth and transition-metal elements (Eu{sup 2+} and Ru{sup 2+}) results inmore » a significantly higher oxidation temperature compared to that of CeFe{sub 4}Sb{sub 12}. This increase can be related to the increased orbital overlap provided by these larger atoms (Eu{sup 2+} and Ru{sup 2+} vs Ce{sup 3+} and Fe{sup 2+}), enabling the development of stronger bonds. These results show how selective substitution of the constituent elements can significantly improve the thermal stability of materials.« less
  • Trace amounts of H/sub 2/O and limited exposure to air of reaction mixtures of UCl/sub 4/ and 12-crown-4, 15-crown-5, benzo-15-crown-5, 18-crown-6, or dibenzo-18-crown-6 in 1:3 mixtures of CH/sub 3/OH and CH/sub 3/CN resulted in the hydrolysis and oxidation of UCl/sub 4/ to (UO/sub 2/Cl/sub 4/)/sup 2/minus//. In the presence of these crown ethers, it has been possible to isolate intermediate products via crystallization of crown complexes of the (UO/sub 2/Cl/sub 4/)/sup 2/minus// ion, the (UCl/sub 6/)/sup 2/minus// ion, and (UO/sub 2/Cl/sub 2/(OH/sub 2/)/sub 3/). The neutral moiety crystallizes as a hydrogen-bonded crown ether complex; however, crown ether complexation of amore » counterion, either an ammonium ion formed during the oxidation of U(IV) or a Na/sup +/ ion leached from glass reaction vessels, resulted in novel crystalline complexes of the ionic species. ((NH/sub 4/)(15-crown-5)/sub 2/)/sub 2/(UO/sub 2/Cl/sub 4/) /times/ 2CH/sub 3/CN, ((NH/sub 4/)(benzo-15-crown-5)/sub 2/)/sub 2/(UCl/sub 6/) /times/ 4CH/sub 3/CN, and ((NH/sub 4/)(dibenzo-18-crown-6))/sub 2/(UO/sub 2/Cl/sub 4/) /times/ 2CH/sub 3/CN have been structurally characterized by single-crystal X-ray diffraction techniques. The results of all the crystal studies are presented in detail. The ammonium ions interact with the crown ethers via hydrogen-bonding and electrostatic interactions. 15-Crown-5 and benzo-15-crown-5 form 2:1 sandwich cations, allowing no H/sub 4/N/sup +//hor ellipsis/(UO/sub 2/Cl/sub 4/)/sup 2/minus// interaction. The dibenzo-18-crown-6 complexed ammonium ions are 1:1 and form bifurcated hydrogen bonds with the chlorine atoms in the (UO/sub 2/Cl/sub 4/)/sup /minus// anion. The formation of (Na(12-crown-4)/sub 2//sub 2/(UO/sub 2/Cl/sub 4/) /times/ 2OHMe and (UO/sub 2/Cl/sub 2/(OH)/sub 2/)/sub 3/) /times/ 18-crown-6 /times/ H/sub 2/O /times/ OHMe has been confirmed by preliminary single-crystal X-ray diffraction studies.« less