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arXiv · 1208.5652

NMR Search for the Spin Nematic State in LaFeAsO Single Crystal

M. Fu·D. A. Torchetti·T. Imai·F. L. Ning·J. -Q. Yan·A. S. Sefat
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Abstract

We report a 75-As single crystal NMR investigation of LaFeAsO, the parent phase of a pnictide high Tc superconductor. We demonstrate that spin dynamics develop a strong two-fold anisotropy within each orthorhombic domain below the tetragonal-orthorhombic structural phase transition at T[TO]~156 K. This intermediate state with a dynamical breaking of the rotational symmetry freezes progressively into a spin density wave (SDW) below T[SDW]~142 K. Our findings are consistent with the presence of a spin nematic state below T[TO] with an incipient magnetic order.

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M. Fu, D. A. Torchetti, T. Imai, F. L. Ning, J. -Q. Yan, A. S. Sefat. 2012-08-28. NMR Search for the Spin Nematic State in LaFeAsO Single Crystal. https://doi.org/10.1103/physrevlett.109.247001

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