Evidence of Nematicity in K_0.8Fe_1.7Se₂

Journal Article · Fri Dec 11 00:00:00 EST 2015 · Journal of Superconductivity and Novel Magnetism

DOI:https://doi.org/10.1007/s10948-015-3327-8· OSTI ID:1324169

Duan, Chunruo ^[1]; Yang, Junjie ^[1]; Ye, Feng ^[2]; Louca, Despina ^[1]

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1. Univ. of Virginia, Charlottesville, VA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

We proposed that the superconducting state of K_0.8Fe_1.7Se₂ is phase separated from a non-superconducting magnetic state. These results from a recent neutron diffraction study on a single crystal of K_0.8Fe_1.7Se₂ 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 √5 X√5 X 1 superlattice structure, resulting in an enhancement of the (101) superlattice peak. Moreover, 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 _xz and d _{y z} orbitals. Finally, the orbital fluctuations couple to the magnetic ordering as seen here and may lead to a realization of nematic order in this system.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1324169
• Journal Information: Journal of Superconductivity and Novel Magnetism, Vol. 29, Issue 3; ISSN 1557-1939
• Publisher: Springer
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Superconductivity
Neutron scattering
Vacancies
Nematic phase
KXFE2-YSE2