Temperature dependence of Eu 4f and Eu 5d magnetizations in the filled skutterudite EuFe4Sb12

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.79.014426· OSTI ID:965329

Krishnamurthy, Vemuru ^[1]; Keavney, D. J. ^[2]; Haskel, D. ^[2]; Lang, J. C. ^[2]; Srajer, G. ^[2]; Sales, Brian C ^[3]; Mandrus, David ^[3]; Robertson, J. L. ^[1]

---

1. Oak Ridge National Laboratory (ORNL)
2. Argonne National Laboratory (ANL)
3. ORNL

The element-specific and shell-specific magnetism of Eu in the filled skutterudite ferrimagnet Eu{sub 0.95}Fe{sub 4}Sb{sub 12} has been investigated using Eu M{sub 4,5}- and Eu L{sub 2,3}-edge x-ray magnetic circular dichroism (XMCD) spectroscopy as a function of temperature. Eu L{sub 3}-edge x-ray absorption spectroscopy shows that Eu is mostly in the divalent state. Eu M{sub 5}-edge x-ray absorption spectroscopy, measured by electron yield, shows nearly equal fractions of Eu{sup 2+} and Eu{sup 3+} states because it probes a significant portion of the surface volume which is dominated by the Eu{sup 3+} impurity state. Sum-rule analysis of the Eu M{sub 4,5}-edge XMCD spectrum measured at 4.9 K yielded the 4f spin moment of (7.15 {+-} 0.3){micro}{sub B} per Eu{sup 2+} ion. By comparing the Eu L{sub 2,3}-edge XMCD spectrum in the ferrimagnetic state of Eu{sub 0.95}Fe{sub 4}Sb{sub 12} to that of a divalent Eu reference compound, the clathrate Eu{sub 8}Ga{sub 16}Ge{sub 30}, we show that the 5d spin polarization of Eu in the skutterudite is strongly enhanced by the exchange coupling with the 3d band electrons of Fe, which were shown to have an ordered moment of ?0.21{micro}{sub B}/Fe in our earlier Fe L{sub 2,3} XMCD measurements. The temperature dependence of the magnetic order parameter, determined from the Eu L{sub 3}-edge XMCD intensity, yields a mean-field-like exponent ({approx} 0.52) in the skutterudite and a three-dimensional Heisenberg-type ({approx} 0.36) exponent in the clathrate.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 965329
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 1 Vol. 79; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIMONY ALLOYS
ELECTRONIC STRUCTURE
EUROPIUM ALLOYS
IRON ALLOYS
MAGNETIC CIRCULAR DICHROISM
MAGNETIZATION
ORDER PARAMETERS
TEMPERATURE DEPENDENCE