Article (Scientific journals)
Phase transitions in LaFeAsO: Structural, magnetic, elastic, and transport properties, heat capacity and Mossbauer spectra
McGuire, Michael A; Christianson, Andrew D; Sefat, Athena S et al.
2008In Physical Review. B, Condensed Matter and Materials Physics, 78 (9)
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Keywords :
LaFeAsO; oxypnictide; superconductors
Abstract :
[en] We present results from a detailed experimental investigation of LaFeAsO, the parent material in the series of "FeAs" based oxypnictide superconductors. Upon cooling, this material undergoes a tetragonal-orthorhombic crystallographic phase transition at similar to 160 K followed closely by an antiferromagnetic ordering near 145 K. Analysis of these phase transitions using temperature dependent powder x-ray and neutron-diffraction measurements is presented. A magnetic moment of similar to 0.35 mu(B) per iron is derived from Mossbauer spectra in the low-temperature phase. Evidence of the structural transition is observed at temperatures well above the transition temperature (up to near 200 K) in the diffraction data as well as the polycrystalline elastic moduli probed by resonant ultrasound spectroscopy measurements. The effects of the two phase transitions on the transport properties (resistivity, thermal conductivity, Seebeck coefficient, and Hall coefficient), heat capacity, and magnetization of LaFeAsO are also reported, including a dramatic increase in the magnitude of the Hall coefficient below 160 K. The results suggest that the structural distortion leads to a localization of carriers on Fe, producing small local magnetic moments which subsequently order antiferromagnetically upon further cooling. Evidence of strong electron-phonon interactions in the high-temperature tetragonal phase is also observed.
Disciplines :
Physics
Author, co-author :
McGuire, Michael A
Christianson, Andrew D
Sefat, Athena S
Sales, Brian C
Lumsden, Mark D
Jin, Rongying
Payzant, E Andrew
Mandrus, David
Luan, Yanbing
Keppens, Veerle
Varadarajan, Vijayalaksmi
Brill, Joseph W
Hermann, Raphaël ;  Université de Liège - ULiège > Département de physique > Département de physique
Sougrati, Moulay Tahar ;  Université de Liège - ULiège > Département de physique > Département de physique
Grandjean, Fernande ;  Université de Liège - ULiège > Département de physique > Département de physique
Long, Gary J
More authors (6 more) Less
Language :
English
Title :
Phase transitions in LaFeAsO: Structural, magnetic, elastic, and transport properties, heat capacity and Mossbauer spectra
Publication date :
2008
Journal title :
Physical Review. B, Condensed Matter and Materials Physics
ISSN :
1098-0121
eISSN :
1550-235X
Publisher :
American Physical Society, College Pk, United States - Maryland
Volume :
78
Issue :
9
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 23 January 2009

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