Paramagnetic spin correlations in CaFe2As2 single crystals

S. O. Diallo, D. K. Pratt, R. M. Fernandes, W. Tian, J. L. Zarestky, M. Lumsden, T. G. Perring, C. L. Broholm, N. Ni, S. L. Bud'Ko, P. C. Canfield, H. F. Li, D. Vaknin, A. Kreyssig, A. I. Goldman, R. J. McQueeney

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

Magnetic correlations in the paramagnetic phase of CaFe2As 2 (TN =172K) have been examined by means of inelastic neutron scattering from 180 K (∼1.05 TN) up to 300 K (1.8 TN). Despite the first-order nature of the magnetic ordering, strong but short-ranged antiferromagnetic (AFM) correlations are clearly observed. These correlations, which consist of quasielastic scattering centered at the wave vector QAFM of the low-temperature AFM structure, are observed up to the highest measured temperature of 300 K and at high energy transfer (ω>60meV). The L dependence of the scattering implies rather weak interlayer coupling in the tetragonal c direction corresponding to nearly two-dimensional fluctuations in the (ab) plane. The spin correlation lengths within the Fe layer are found to be anisotropic, consistent with underlying fluctuations of the AFM stripe structure. Similar to the cobalt-doped superconducting BaFe2 As2 compounds, these experimental features can be adequately reproduced by a scattering model that describes short-ranged and anisotropic spin correlations with overdamped dynamics.

Original languageEnglish (US)
Article number214407
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume81
Issue number21
DOIs
StatePublished - Jun 7 2010

Fingerprint Dive into the research topics of 'Paramagnetic spin correlations in CaFe<sub>2</sub>As<sub>2</sub> single crystals'. Together they form a unique fingerprint.

  • Cite this

    Diallo, S. O., Pratt, D. K., Fernandes, R. M., Tian, W., Zarestky, J. L., Lumsden, M., Perring, T. G., Broholm, C. L., Ni, N., Bud'Ko, S. L., Canfield, P. C., Li, H. F., Vaknin, D., Kreyssig, A., Goldman, A. I., & McQueeney, R. J. (2010). Paramagnetic spin correlations in CaFe2As2 single crystals. Physical Review B - Condensed Matter and Materials Physics, 81(21), [214407]. https://doi.org/10.1103/PhysRevB.81.214407