Abstract
It has been proposed that the superconducting state of K0.8Fe1.7Se2 is phase separated from a non-superconducting magnetic state. The results from a recent neutron diffraction study on a single crystal of K0.8Fe1.7Se2 provide evidence for a continuous transition between the I4/m m m high temperature phase in which the Fe vacancies are randomly distributed and the I4/m vacancy ordered phase in the temperature range between T C and T S. Upon cooling, the I4/m phase becomes more populated, increasing the \(\sqrt {5}\times \sqrt {5}\times 1\) superlattice structure, resulting in an enhancement of the (101) superlattice peak. The same temperature dependence is observed for the magnetic peak as well. Moreover, due to the Fe site splitting with the transition, its z-coordinate fluctuates, and so must the d x z and d y z orbitals. The orbital fluctuations couple to the magnetic ordering as seen here and may lead to a realization of nematic order in this system.
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References
Guo, J., et al.: Superconductivity in the iron selenide K x Fe2Se2 (0 ≤ x≤1.0). Phys. Rev. B 82, 180520 (2010)
Bao, W., et al.: A novel large moment antiferromagnetic order in K0.8Fe1.6Se2 superconductor. Chin. Phys. Lett. 28, 086104 (2011)
Ding, X., et al.: Influence of microstructure on superconductivity in K x Fe2−y Se2 and evidence for a new parent phase K2Fe7Se8. Nature Commun. 4, 1894 (2013)
Yan, Y.J., et al.: Electronic and magnetic phase diagram in K x Fe2−y Se2 superconductors. Nature Scientific Reports 2, 00212 (2012)
Ricci, A., et al.: Nanoscale phase separation in the iron chalcogenides superconductor K0.8Fe1.6Se2 as seen via scanning nanofocused x-ray diffraction. Phys. Rev. B 84, 060511 (2011)
Ye, F., et al.: Common crystalline and magnetic structure of superconducting A2Fe4Se5 (A=K, Rb,Cs,Tl) single crystals measured using neutron diffraction. Phys. Rev. Lett. 107, 137003 (2011)
Zavalij, P., et al.: Structure of vacancy-ordered single-crystalline superconducting potassium iron selenide. Phys. Rev. B 83, 132509 (2011)
Li, W., et al.: Phase separation and magnetic order in K-doped iron selenide superconductor. Nat. Phys. 8, 126–130 (2012)
Wang, D.M., et al.: Effect of varying iron content on the transport properties of the potassium-intercalated iron selenide K x Fe2−y Se2. Phys. Rev. B 83, 132502 (2011)
Fernandes, R.M., et al.: What drives nematic order in iron-based superconductors? Nat. Phys. 10, 97104 (2014)
Liang, S., et al.: Nematic state of pnictides stabilized by interplay between spin, orbital, and lattice degrees of freedom. Phys. Rev. Lett. 111, 047004 (2013)
Louca, D., et al.: The hybrid lattice of K x Fe2−y Se2: why superconductivity and magnetism can coexist. Nature Scientific Report 3, 2047 (2013)
Yang, J., et al.: Fe vacancies and magnetic ordering in the superconducting state of K0.8Fe2−y Se2, submitted (2015)
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Duan, C., Yang, J., Ye, F. et al. Evidence of Nematicity in K0.8Fe1.7Se2 . J Supercond Nov Magn 29, 663–666 (2016). https://doi.org/10.1007/s10948-015-3327-8
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DOI: https://doi.org/10.1007/s10948-015-3327-8