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Title: Control of the third dimension in copper-based square-lattice antiferromagnets

Using a mixed-ligand synthetic scheme, we create a family of quasi-two-dimensional antiferromagnets, namely, [Cu(HF2)(pyz)2]ClO4 [pyz = pyrazine], [CuL2(pyz)2](ClO4)2 [L = pyO = pyridine-N-oxide and 4-phpy-O = 4-phenylpyridine-N-oxide. These materials are shown to possess equivalent two-dimensional [Cu(pyz)2]2+ nearly square layers, but exhibit interlayer spacings that vary from 6.5713 to 16.777 Å, as dictated by the axial ligands. We present the structural and magnetic properties of this family as determined via x-ray diffraction, electron-spin resonance, pulsed- and quasistatic-field magnetometry and muon-spin rotation, and compare them to those of the prototypical two-dimensional magnetic polymer Cu(pyz)2(ClO4)2. We find that, within the limits of the experimental error, the two-dimensional, intralayer exchange coupling in our family of materials remains largely unaffected by the axial ligand substitution, while the observed magnetic ordering temperature (1.91 K for the material with the HF2 axial ligand, 1.70 K for the pyO and 1.63 K for the 4-phpy-O) decreases slowly with increasing layer separation. Despite the structural motifs common to this family and Cu(pyz)2(ClO4)2, the latter has significantly stronger two-dimensional exchange interactions and hence a higher ordering temperature. Here, we discuss these results, as well as the mechanisms that might drive the long-range order in these materials, in terms of departuresmore » from the ideal S = 1/2 two-dimensional square-lattice Heisenberg antiferromagnet. In particular, we find that both spin-exchange anisotropy in the intralayer interaction and interlayer couplings (exchange, dipolar, or both) are needed to account for the observed ordering temperatures, with the intralayer anisotropy becoming more important as the layers are pulled further apart.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [1] ;  [1] ;  [11] ;  [12] ;  [13] ;  [14] ;  [15] ;  [14] more »;  [14] ;  [15] ;  [14] « less
  1. Univ. of Warwick, Coventry (United Kingdom)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Oxford, Oxford (United Kingdom)
  3. Univ. of Oxford, Oxford (United Kingdom); Helios, Farnborough (United Kingdom)
  4. Univ. of Oxford, Oxford (United Kingdom); ETH Zurich, Zurich (Switzerland)
  5. Durham Univ., Durham (United Kingdom)
  6. Univ. of Oxford, Oxford (United Kingdom)
  7. STFC Rutherford Appleton Lab., Oxfordshire (United Kingdom)
  8. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  9. Univ. of Copenhagen, Copenhagen (Denmark)
  10. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  11. State Univ. of New York, Stony Brook, NY (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
  12. State Univ. of New York, Stony Brook, NY (United States)
  13. Univ. of Idaho, Moscow, ID (United States)
  14. Eastern Washington Univ., Cheney, WA (United States)
  15. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
OSTI Identifier:
1338801
Report Number(s):
LA-UR--16-21872
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 93; Journal Issue: 9; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY High Magnetic Field Science