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Title: Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb 2 Ti 2 O 7

Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field Hamiltonian, eigenvalues and eigenvectors appropriate to the J=7/2 Yb 3+ ion in the candidate quantum spin ice pyrochlore magnet Yb 2Ti 2O 7. The precise ground state of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak “stuffing,” wherein a small proportion, approximately 2%, of the nonmagnetic Ti 4+ sites are occupied by excess Yb 3+. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb 2Ti 2O 7, as well as a crushed single crystal with weak stuffing and an approximate composition of Yb 2+xTi 2–xO 7+y with x = 0.046. All samples display three crystalline electric field transitions out of the ground state, and the ground state doublet itself is identified as primarily composed of m J = ±1/2, as expected. However, stuffing at low temperatures in Yb 2+xTi 2–xO 7+y induces a similar finite crystalline electric field lifetime as is induced in stoichiometric Yb 2Ti 2O 7 by elevated temperature. In conclusion, an extended strain field exists about each local “stuffed” site, whichmore » produces a distribution of random crystalline electric field environments in the lightly stuffed Yb 2+xTi 2–xO 7+y, in addition to producing a small fraction of Yb ions in defective environments with grossly different crystalline electric field eigenvalues and eigenvectors.« less
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5]
  1. McMaster Univ., Hamilton, ON (Canada)
  2. Colorado State Univ., Fort Collins, CO (United States)
  3. Brockhouse Institute for Materials Research, Hamilton, ON (Canada)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. McMaster Univ., Hamilton, ON (Canada); Brockhouse Institute for Materials Research, Hamilton, ON (Canada); Canadian Institute for Materials Research, Toronto, ON (Canada)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 92; Journal Issue: 13; Journal ID: ISSN 1098-0121
American Physical Society (APS)
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)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1224372