Volume 111, Number 2, July 2015
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||18 August 2015|
Disordered Fe vacancies and superconductivity in potassium-intercalated iron selenide (K2−xFe4+ySe5)
1 Institute of Physics, Academia Sinica - Taipei, Taiwan
2 Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology Taipei, Taiwan
3 Department of Physics, National Tsing Hua University - Hsinchu, Taiwan
4 Institute of Astrophysics and Astronomy, Academia Sinica - Taipei, Taiwan
5 Deparment of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University Stanford, CA, USA
6 National Donghwa University - Hualien, Taiwan
Received: 1 June 2015
Accepted: 20 July 2015
In the high-Tc potassium-intercalated FeSe, there has been significant debate regarding what the exact parent compound is. Here we 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 as to 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.
PACS: 74.25.-q – Properties of superconductors / 74.62.En – Effects of disorder / 74.25.F- – Transport properties
© EPLA, 2015
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