Magneto-elastically coupled structural, magnetic and superconducting order parameters in BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$
Authors:
H-. H. Kuo,
James G. Analytis,
J. -H. Chu,
R. M. Fernandes,
J. Schmalian,
I. R. Fisher
Abstract:
We measure the transport properties of mechanically strained single crystals of BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ over a wide range of $x$. The Néel transition is extremely sensitive to stress and this sensitivity increases as optimal doping is approached, even though the transition itself is strongly suppressed. Furthermore, we observe significant changes in the superconducting transition tempe…
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We measure the transport properties of mechanically strained single crystals of BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ over a wide range of $x$. The Néel transition is extremely sensitive to stress and this sensitivity increases as optimal doping is approached, even though the transition itself is strongly suppressed. Furthermore, we observe significant changes in the superconducting transition temperature with applied strain, which mirror changes as a function of the composition $x$. These experiments are a direct illustration of the intimate coupling between different degrees of freedom in iron-based superconductors, revealing the importance of magneto-elastic coupling to the magnetic and superconducting transition temperatures.
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Submitted 16 July, 2012;
originally announced July 2012.
Resonant Enhancement of Charge Density Wave Diffraction in the Rare-Earth Tritellurides
Authors:
W. S. Lee,
A. P. Sorini,
M. Yi,
Y. D. Chuang,
B. Moritz,
W. L. Yang,
J. -H. Chu,
H. H. Kuo,
A. G. Cruz Gonzalez,
I. R. Fisher,
Z. Hussain,
T. P. Devereaux,
Z. X. Shen
Abstract:
We performed resonant soft X-ray diffraction on known charge density wave (CDW) compounds, rare earth tri-tellurides. Near the $M_5$ (3d - 4f) absorption edge of rare earth ions, an intense diffraction peak is detected at a wavevector identical to that of CDW state hosted on Te$_2$ planes, indicating a CDW-induced modulation on the rare earth ions. Surprisingly, the temperature dependence of the d…
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We performed resonant soft X-ray diffraction on known charge density wave (CDW) compounds, rare earth tri-tellurides. Near the $M_5$ (3d - 4f) absorption edge of rare earth ions, an intense diffraction peak is detected at a wavevector identical to that of CDW state hosted on Te$_2$ planes, indicating a CDW-induced modulation on the rare earth ions. Surprisingly, the temperature dependence of the diffraction peak intensity demonstrates an exponential increase at low temperatures, vastly different than that of the CDW order parameter. Assuming 4f multiplet splitting due to the CDW states,we present a model to calculate X-ray absorption spectrum and resonant profile of the diffraction peak, agreeing well with experimental observations. Our results demonstrate a situation where the temperature dependence of resonant X-ray diffraction peak intensity is not directly related to the intrinsic behavior of the order parameter associated with the electronic order, but is dominated by the thermal occupancy of the valence states.
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Submitted 30 April, 2012;
originally announced May 2012.