Title: Negative Thermal Expansion and Antiferromagnetism in the Actinide Oxypnictide NpFeAsO
Authors: KLIMCZUK TOMASZWALKER H.c.SPRINGELL R.SHIK ALEXANDERHILL A. H.GACZYNSKI PiotrGOFRYK KrzysztofKIMBER S. A. J.RITTER C.COLINEAU EricGRIVEAU Jean-ChristopheBOUEXIERE DanielELOIRDI RachelCAVA R. J.CACIUFFO Roberto
Citation: PHYSICAL REVIEW B vol. 85 no. 17 p. 174506-10
Publisher: AMER PHYSICAL SOC
Publication Year: 2012
JRC N°: JRC70538
ISSN: 1098-0121
URI: http://prb.aps.org/abstract/PRB/v85/i17/e174506
http://publications.jrc.ec.europa.eu/repository/handle/JRC70538
DOI: 10.1103/PhysRevB.85.174506
Type: Articles in Journals
Abstract: A neptunium analog of the LaFeAsO tetragonal layered compound has been synthesized and characterized by a variety of experimental techniques. The occurrence of long-range magnetic order below a critical temperature TN = 57 K is suggested by anomalies in the temperature-dependent magnetic susceptibility, electrical resistivity, Hall coefficient, and specific-heat curves. Below TN, powder neutron diffraction measurements reveal an antiferromagnetic structure of the Np sublattice, with an ordered magnetic moment of 1.70 ± 0.07μB aligned along the crystallographic c axis. No magnetic order has been observed on the Fe sublattice, setting an upper limit of about 0.3μB for the ordered magnetic moment on the iron. High-resolution x-ray powder diffraction measurements exclude the occurrence of lattice transformations down to 5K, in sharp contrast to the observation of a tetragonal-to-orthorhombic distortion in the rare-earth analogs, which has been associated with the stabilization of a spin-density wave on the iron sublattice. Instead, a significant expansion of the NpFeAsO lattice parameters is observed with decreasing temperature below TN, corresponding to a relative volume change of about 0.2% and to an Invar behavior between 5 and 20 K. First-principles electronic structure calculations based on the local spin density plus Coulomb interaction and the local density plus Hubbard-I approximations provide results in good agreement with the experimental findings.
JRC Institute:Institute for Transuranium Elements

Files in This Item:
There are no files associated with this item.


Items in repository are protected by copyright, with all rights reserved, unless otherwise indicated.