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Title: Competing spin density wave, collinear, and helical magnetism in Fe 1 + x Te

The Fe 1+xTe phase diagram consists of two distinct magnetic structures with collinear order present at low interstitial iron concentrations and a helical phase at large values of x with these phases separated by a Lifshitz point. In this paper, we use unpolarized single-crystal diffraction to confirm the helical phase for large interstitial iron concentrations and polarized single-crystal diffraction to demonstrate the collinear order for the iron-deficient side of the Fe 1+xTe phase diagram. Polarized neutron inelastic scattering shows that the fluctuations associated with this collinear order are predominately transverse at low-energy transfers, consistent with a localized magnetic moment picture. We then apply neutron inelastic scattering and polarization analysis to investigate the dynamics and structure near the boundary between collinear and helical orders in the Fe 1+xTe phase diagram. We first show that the phase separating collinear and helical orders is characterized by a spin density wave with a single propagation wave vector of (~0.45, 0, 0.5). We do not observe harmonics or the presence of a charge density wave. The magnetic fluctuations associated with this wave vector are different from the collinear phase, being strongly longitudinal in nature and correlated anisotropically in the (H,K) plane. The excitations preserve themore » C 4 symmetry of the lattice but display different widths in momentum along the two tetragonal directions at low-energy transfers. Finally, while the low-energy excitations and minimal magnetic phase diagram can be understood in terms of localized interactions, we suggest that the presence of the density wave phase implies the importance of electronic and orbital properties.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [6] ;  [7]
  1. Univ. of Edinburgh, Scotland (United Kingdom). School of Physics and Astronomy
  2. Univ. of Maryland, College Park, MD (United States). Dept. of Chemistry of Biochemistry
  3. Alternative Energies and Atomic Energy Commission (CEA-CNRS), Gif-sur-Yvette (France). Lab. Leon Brillouin
  4. Rutherford Appleton Lab., Didcot (United Kingdom). ISIS Facility
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  6. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). NIST Center for Neutron Research; Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science
  7. Univ. of Kent, Canterbury (United Kingdom). School of Physical Sciences
Publication Date:
Grant/Contract Number:
AC05-00OR22725; DMR-09447720
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 14; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Edinburgh, Scotland (United Kingdom); Rutherford Appleton Lab., Didcot (United Kingdom)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Royal Society of Edinburgh; Engineering and Physical Sciences Research Council (EPSRC)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; antiferromagnetism; magnetic phase transitions; superconducting phase transition
OSTI Identifier:
1427594
Alternate Identifier(s):
OSTI ID: 1350790