J. Phys.: Condens. Matter 21 (28 October 2009) 432201 (6pp) doi: 10.1088/0953-8984/21/43/432201
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RE L3 x-ray
absorption study of REO1−xFxFeAs
(RE = La, Pr, Nd, Sm) oxypnictides
B Joseph1, A Iadecola1, M Fratini2, A Bianconi1, A Marcelli3 and N L Saini1
1 Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazza le Aldo Moro 2, 00185
Roma,
Italy
2 Istituto di Fotonica e Nanotecnologie, CNR Roma,
Italy
3 Laboratori Nazionali di Frascati, INFN, 00044 Frascati,
ItalyAbstract.
Rare earth L3-edge x-ray absorption near-edge structure (XANES) spectroscopy has been used to study REOFeAs (RE = La, Pr, Nd, Sm)
oxypnictides. The Nd L3
XANES due to the 
transition shows a substantial change in both white line (WL) spectral weight and
the higher energy multiple scattering resonances with the partial substitution
of O by F. A systematic change in the XANES features is seen due to varying
lattice parameters with ionic radius of the rare earth. On the other hand, we
hardly see any change across the structural phase transition. The results provide
timely information on the local atomic correlations showing the importance of the
local structural chemistry of the REO spacer layer and interlayer coupling in
the competing superconductivity and itinerant striped magnetic phase of the
oxypnictides.
Print publication: Issue 43 (28 October 2009)Received 4 August 2009, in final form 22 September 2009
Published 8 October 2009
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