Iron-vacancy superstructure and possible room temperature antiferromagnetic order in superconducting CsyFe2-xSe2

V. Yu. Pomjakushin , D. V. Sheptyakov , E. V. Pomjakushina , Anna Krztoń-Maziopa , K. Conder , D. Chernyshov , V. Svitlyk , Z. Shermadini

Abstract

Neutron and x-ray powder and single crystal synchrotron diffraction of CsyFe2−xSe2 show the presence of superstructure reflections with propagation vector k=[25,15,1] with respect to the average crystal structure I4/mmm (a~4,c~15 Å). The propagation vector star corresponds to the 5 times bigger unit cell given by transformation A=2a+b, B=−a+2b, C=c. A solution for the atomic structure is found in the space group I4/m with an ordered pattern of iron vacancies corresponding to the iron deficiency x=0.29 and Cs stoichiometry y=0.83. The superstructure satellites are more pronounced in the neutron diffraction patterns suggesting that they can have some magnetic contribution. We have sorted out all possible symmetry adapted magnetic configurations and found that the presence of antiferromagnetic ordering with the ordered magnetic moment of Fe with ≃2μB does not contradict the experimental data. However, the solutions space is highly degenerate and we cannot choose a specific solution. Instead we propose possible magnetic configurations with the Fe magnetic moments in (ab) plane or along c axis. The superstructure is destroyed above Ts≃500 K by a first-order-like transition.
Author V. Yu. Pomjakushin
V. Yu. Pomjakushin,,
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, D. V. Sheptyakov
D. V. Sheptyakov,,
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, E. V. Pomjakushina
E. V. Pomjakushina,,
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, Anna Krztoń-Maziopa KChNTCS
Anna Krztoń-Maziopa,,
- Chair Of Inorganic Chemistry And Solid State Technology
, K. Conder
K. Conder,,
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, D. Chernyshov
D. Chernyshov,,
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, V. Svitlyk
V. Svitlyk,,
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, Z. Shermadini
Z. Shermadini,,
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Journal seriesPhysical Review B, ISSN 1098-0121
Issue year2011
Vol83
No14
Pages144410
DOIDOI:10.1103/PhysRevB.83.144410
URL http://link.aps.org/doi/10.1103/PhysRevB.83.144410
Languageen angielski
File
Iron vacancy superstructure and possible AFM order in CsyFe2-xSe2- PhysRevB 83 -2011.pdf (file archived - login or check accessibility on faculty) Iron vacancy superstructure and possible AFM order in CsyFe2-xSe2- PhysRevB 83 -2011.pdf 436.23 KB
Score (nominal)35
Publication indicators WoS Impact Factor: 2011 = 3.691 (2) - 2011=3.405 (5)
Citation count*92 (2015-11-27)
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