Skip to main content

Negative thermal expansion and antiferromagnetism in the actinide oxypnictide NpFeAsO

Author(s): Klimczuk, Tomasz W.; Walker, Helen C.; Springell, Ross S.; Shick, Alexander B.; Hill, Adrian H.; et al

To refer to this page use:
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 T N = 57 K is suggested by anomalies in the temperature-dependent magnetic susceptibility, electrical resistivity, Hall coefficient, and specific-heat curves. Below T N, powder neutron diffraction measurements reveal an antiferromagnetic structure of the Np sublattice, with an ordered magnetic moment of 1.70 ± 0.07μ B aligned along the crystallographic c axis. No magnetic order has been observed on the Fe sublattice, setting an upper limit of about 0.3μ B for the ordered magnetic moment on the iron. High-resolution x-ray powder diffraction measurements exclude the occurrence of lattice transformations down to 5 K, 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 T N, 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. © 2012 American Physical Society.
Publication Date: May-2012
Electronic Publication Date: 9-May-2012
Citation: Klimczuk, T., Walker, H.C., Springell, R., Shick, A.B., Hill, A.H., Gaczyński, P., Gofryk, K., Kimber, S.A.J., Ritter, C., Colineau, E., Griveau, J.C., Bouëxière, D., Eloirdi, R., Cava, R.J., Caciuffo, R. (2012). Negative thermal expansion and antiferromagnetism in the actinide oxypnictide NpFeAsO. Physical Review B, 85 (17), 10.1103/PhysRevB.85.174506
DOI: doi:10.1103/PhysRevB.85.174506
ISSN: 1098-0121
EISSN: 1550-235X
Pages: 85.17:174506-1 - 174506-10
Type of Material: Journal Article
Journal/Proceeding Title: Physical Review B
Version: Final published version. Article is made available in OAR by the publisher's permission or policy.
Notes: Physical Review B - Condensed Matter and Materials Physics. Volume 85, Issue 17, 9 May 2012, Article number 174506.

Items in OAR@Princeton are protected by copyright, with all rights reserved, unless otherwise indicated.