Open AccessNew superconductor LixFe1+δSe (x ≤ 0.07, Tc up to 44 K) by an electrochemical route
Author(s) -
Anastasia M. Alekseeva,
Oleg A. Drozhzhin,
Kirill A. Dosaev,
Evgeny V. Antipov,
Konstantin V. Zakharov,
О. С. Волкова,
Д. А. Чареев,
A. N. Vasiliev,
Cevriye Koz,
Ulrich Schwarz,
H. Rösner,
Yuri Grin
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep25624
Subject(s) - tetragonal crystal system , electrochemistry , lithium (medication) , fermi level , superconductivity , electronic structure , materials science , crystallography , chemistry , crystal structure , condensed matter physics , electrode , physics , computational chemistry , medicine , quantum mechanics , endocrinology , electron
The superconducting transition temperature ( T c ) of tetragonal Fe 1+δ Se was enhanced from 8.5 K to 44 K by chemical structure modification. While insertion of large alkaline cations like K or solvated lithium and iron cations in the interlayer space, the [Fe 2 Se 2 ] interlayer separation increases significantly from 5.5 Å in native Fe 1+δ Se to >7 Å in K x Fe 1− y Se and to >9 Å in Li 1− x Fe x (OH)Fe 1− y Se, we report on an electrochemical route to modify the superconducting properties of Fe 1+δ Se. In contrast to conventional chemical (solution) techniques, the electrochemical approach allows to insert non-solvated Li + into the Fe 1+δ Se structure which preserves the native arrangement of [Fe 2 Se 2 ] layers and their small separation. The amount of intercalated lithium is extremely small (about 0.07 Li + per f.u.), however, its incorporation results in the enhancement of T c up to ∼44 K. The quantum-mechanical calculations show that Li occupies the octahedrally coordinated position, while the [Fe 2 Se 2 ] layers remain basically unmodified. The obtained enhancement of the electronic density of states at the Fermi level clearly exceeds the effect expected on basis of rigid band behavior.