Wednesday, August 29, 2012

1208.5652 (M. Fu et al.)

NMR Search for the Spin Nematic State in LaFeAsO Single Crystal    [PDF]

M. Fu, D. A. Torchetti, T. Imai, F. L. Ning, J. -Q. Yan, A. S. Sefat
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.
View original: http://arxiv.org/abs/1208.5652

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