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arXiv · 1502.01116

Disordered Fe vacancies and superconductivity in potassium-intercalated iron selenide (K2-xFe4+ySe5)

Chih-Han Wang·Ta-Kun Chen·Chung-Chieh Chang·Chia-Hao Hsu·Yung-Chi Lee·Ming-Jye Wang·Phillip M. Wu·Maw-Kuen Wu
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Abstract

The parent compound of an unconventional superconductor must contain unusual correlated electronic and magnetic properties of its own. In the high-Tc potassium intercalated FeSe, there has been significant debate regarding what the exact parent compound is. Our studies unambiguously show that the Fe-vacancy ordered K2Fe4Se5 is the magnetic, Mott insulating parent compound of the superconducting state. Non-superconducting K2Fe4Se5 becomes a superconductor after high temperature annealing, and the overall picture indicates that superconductivity in K2-xFe4+ySe5 originates from the Fe-vacancy order to disorder transition. Thus, the long pending question whether magnetic and superconducting state are competing or cooperating for cuprate superconductors may also apply to the Fe-chalcogenide superconductors. It is believed that the iron selenides and related compounds will provide essential information to understand the origin of superconductivity in the iron-based superconductors, and possibly to the superconducting cuprates.

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Chih-Han Wang, Ta-Kun Chen, Chung-Chieh Chang, Chia-Hao Hsu, Yung-Chi Lee, Ming-Jye Wang, Phillip M. Wu, Maw-Kuen Wu. 2015-02-04. Disordered Fe vacancies and superconductivity in potassium-intercalated iron selenide (K2-xFe4+ySe5). https://doi.org/10.1209/0295-5075/111/27004

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