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Title: Neutron diffraction and μ SR studies of two polymorphs of nickel niobate NiNb 2 O 6

Neutron diffraction and muon spin relaxation (μSR) studies are presented in this paper for the newly characterized polymorph of NiNb 2O 6 (β-NiNb 2O 6) with space group P4 2/n and μSR data only for the previously known columbite structure polymorph with space group Pbcn. The magnetic structure of the P4 2/n form was determined from neutron diffraction using both powder and single-crystal data. Powder neutron diffraction determined an ordering wave vector k=( 1/ 2, 1/ 2, 1/ 2). Single-crystal data confirmed the same k vector and showed that the correct magnetic structure consists of antiferromagnetically coupled chains running along the a or b axis in adjacent Ni 2+ layers perpendicular to the c axis, which is consistent with the expected exchange interaction hierarchy in this system. The refined magnetic structure is compared with the known magnetic structures of the closely related trirutile phases, NiSb 2O 6 and NiTa 2O 6. μSR data finds a transition temperature of T N~15K for this system, while the columbite polymorph exhibits a lower T N=5.7(3) K. Our μSR measurements also allowed us to estimate the critical exponent of the order parameter β for each polymorph. We found β =0.25(3) and 0.16(2) for themore » β and columbite polymorphs, respectively. The single-crystal neutron scattering data give a value for the critical exponent β =0.28(3) for β-NiNb 2O 6, in agreement with the μSR value. While both systems have β values less than 0.3, which is indicative of reduced dimensionality, this effect appears to be much stronger for the columbite system. Finally, in other words, although both systems appear to be well described by S=1 spin chains, the interchain interactions in the β polymorph are likely much larger.« less
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [6] ;  [6] ;  [7] ;  [4] ;  [8] ;  [9]
  1. McMaster Univ., Hamilton, ON (Canada). Dept. of Physics and Astronomy
  2. Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry
  3. Canadian Neutron Beam Centre, Chalk River, ON (Canada)
  4. Zhejiang Univ., Hangzhou (China). Dept. of Physics
  5. Columbia Univ., New York, NY (United States). Dept. of Physics
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division. Neutron Sciences Directorate
  7. McMaster Univ., Hamilton, ON (Canada). Brockhouse Inst. for Materials Research
  8. McMaster Univ., Hamilton, ON (Canada). Brockhouse Inst. for Materials Research. Dept. of Chemistry
  9. McMaster Univ., Hamilton, ON (Canada). Dept. of Physics and Astronomy. Brockhouse Inst. for Materials Research; Canadian Inst. for Advanced Research, Toronto, ON (Canada)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 14; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
McMaster Univ., Hamilton, ON (Canada); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Ontario Graduate Scholarship (OGS) (Canada); Natural Sciences and Engineering Research Council of Canada (NSERC)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; antiferromagnetism; crystal growth; frustrated magnetism; magnetic interactions; magnetic order parameter; magnetic phase transitions; order parameters; antiferromagnets; magnetic systems; muon spin relaxation & rotation; neutron diffraction; condensed matter & materials physics
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1399284