Lattice collapse and quenching of magnetism in CaFe2As2 under pressure: A single-crystal neutron and x-ray diffraction investigation

A. I. Goldman, A. Kreyssig, K. Prokeš, D. K. Pratt, D. N. Argyriou, J. W. Lynn, S. Nandi, S. A. J. Kimber, Y. Chen, Y. B. Lee, G. Samolyuk, J. B. Leão, S. J. Poulton, S. L. Bud’ko, N. Ni, P. C. Canfield, B. N. Harmon, and R. J. McQueeney
Phys. Rev. B 79, 024513 – Published 21 January 2009

Abstract

Single-crystal neutron and high-energy x-ray diffraction measurements have identified the phase lines corresponding to transitions among the ambient-pressure paramagnetic tetragonal (T), the antiferromagnetic orthorhombic (O), and the nonmagnetic collapsed tetragonal (cT) phases of CaFe2As2. We find no evidence of additional structures for pressures of up to 2.5 GPa (at 300 K). Both the T-cT and O-cT transitions exhibit significant hysteresis effects, and we demonstrate that coexistence of the O and cT phases can occur if a nonhydrostatic component of pressure is present. Measurements of the magnetic diffraction peaks show no change in the magnetic structure or ordered moment as a function of pressure in the O phase, and we find no evidence of magnetic ordering in the cT phase. Band-structure calculations show that the transition into the cT phase results in a strong decrease in the iron 3d density of states at the Fermi energy, consistent with a loss of the magnetic moment.

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  • Received 12 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.024513

©2009 American Physical Society

Authors & Affiliations

A. I. Goldman1,2, A. Kreyssig1,2, K. Prokeš3, D. K. Pratt1,2, D. N. Argyriou3, J. W. Lynn4, S. Nandi1,2, S. A. J. Kimber3, Y. Chen4,5, Y. B. Lee1,2, G. Samolyuk1,2, J. B. Leão4, S. J. Poulton4,5, S. L. Bud’ko1,2, N. Ni1,2, P. C. Canfield1,2, B. N. Harmon1,2, and R. J. McQueeney1,2

  • 1Ames Laboratory, U.S. DOE, Iowa State University, Ames, Iowa 50011, USA
  • 2Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
  • 3Helmholtz-Zentrum Berlin für Materialien und Energie, Glienicker Straße 100, 14109 Berlin, Germany
  • 4NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
  • 5Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA

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Issue

Vol. 79, Iss. 2 — 1 January 2009

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