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Title: Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce–Yb)

In this study, ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior of A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Finally, polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [3] ;  [6] ;  [1]
  1. Florida State Univ., Tallahassee, FL (United States). Dept. of Chemistry and Biochemistry
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  3. National Research Nuclear Univ., Moscow (Russia). Moscow Engineering Physics Inst.
  4. National Research Nuclear Univ., Moscow (Russia). Moscow Engineering Physics Inst.; European XFEL GmbH, Hamburg (Germany)
  5. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
  6. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Photon Science
Publication Date:
Grant/Contract Number:
AC05-00OR22725; DMR-1507233; 14-22-00098
Type:
Accepted Manuscript
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 236; Journal ID: ISSN 0022-4596
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Russian Science Foundation
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Flux synthesis; Crystal growth; Arsenides; Itinerant magnetism; Mixed valence
OSTI Identifier:
1261277
Alternate Identifier(s):
OSTI ID: 1279011