Detection of orbital fluctuations above the structural transition temperature in the iron pnictides and chalcogenides

Date
2012-06-01
Authors
Arham, H. Z.
Hunt, C. R.
Park, W. K.
Gillett, J.
Das, S. D.
Sebastian, S. E.
Xu, Z. J.
Wen, J. S.
Lin, Z. W.
Li, Q.
Gu, G.
Thaler, A.
Ran, S.
Bud’ko, Sergey
Canfield, Paul
Chung, D. Y.
Kanatzidis, M. G.
Greene, L. H.
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Ames Laboratory
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Physics and Astronomy
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We use point-contact spectroscopy (PCS) to probe AEFe2As2 (AE=Ca,Sr,Ba) and Fe1+yTe. For AE=Sr,Ba we detect orbital fluctuations above TS while for AE=Ca these fluctuations start below TS. 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 Fe1+yTe above TS. Our data are examined in light of the recent work by Lee and Phillips (arXiv:1110.5917v2). We also study how joule heating in the PCS junctions impacts the spectra. Spectroscopic information is only obtained from those PCS junctions that are free of heating effects while those PCS junctions that are in the thermal regime display bulk resistivity phenomena.

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This article is published as Arham, H. Z., C. R. Hunt, W. K. Park, J. Gillett, S. D. Das, S. E. Sebastian, Z. J. Xu et al. "Detection of orbital fluctuations above the structural transition temperature in the iron pnictides and chalcogenides." Physical Review B 85, no. 21 (2012): 214515. DOI: 10.1103/PhysRevB.85.214515. Posted with permission.

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