Competing spin density wave, collinear, and helical magnetism in Fe1+xTe

C. Stock*, E. E. Rodriguez, P. Bourges, R. A. Ewings, H. Cao, S. Chi, J. A. Rodriguez-Rivera, M. A. Green

*Corresponding author for this work

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Abstract / Description of output

The Fe1+x Te 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. 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 Fe1+x Te 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 Fe1+x Te 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 (similar to 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 the C-4 symmetry of the lattice but display different widths in momentum along the two tetragonal directions at low-energy transfers. 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.

Original languageEnglish
Article number144407
Number of pages12
JournalPhysical Review B
Issue number14
Publication statusPublished - 7 Apr 2017

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