1201.2479 (H. Z. Arham et al.)

Detection of Orbital Fluctuations Above the Structural Transition
Temperature in the Iron-Pnictides and Chalcogenides    [PDF]

H. Z. Arham, C. R. Hunt, W. K. Park, J. Gillett, S. D. Das, S. E. Sebastian, Z. J. Xu, J. S. Wen, Z. W. Lin, Q. Li, G. Gu, A. Thaler, S. Ran, S. L. Bud'ko, P. C. Canfield, D. Y. Chung, M. G. Kanatzidis, L. H. Greene

We use point contact spectroscopy to probe $\rm{AEFe_2As_2}$ ($\rm{AE=Ca, Sr, Ba}$) and $\rm{Fe_{1+y}Te}$. For $\rm{AE=Sr, Ba}$ we detect orbital fluctuations above $T_S$ while for AE=Ca these fluctuations start below $T_S$. Co doping preserves the orbital fluctuations while K doping suppresses it. The fluctuations are only seen at those dopings and temperatures where an in-plane resistive anisotropy is known to exist. We predict an in-plane resistive anisotropy of $\rm{Fe_{1+y}Te}$ above $T_S$. Our data are examined in light of the recent work by W.-C. Lee and P. Phillips (arXiv:1110.5917v1).

View original: http://arxiv.org/abs/1201.2479