Synthesis of New Lithium- and Monoamine-Intercalated Superconductors Li$_x$(C$_n$H$_{2n+3}$N)$_y$Fe$_{1-z}$Se ($n$ = 6, 8, 18) with the Dramatically Expanded Interlayer Spacing

TL;DR

This paper reports the synthesis of new FeSe-based superconductors intercalated with lithium and monoamines, achieving unprecedented interlayer spacing up to 55.7 Å while maintaining a superconducting transition temperature around 42 K.

Contribution

The study introduces a novel co-intercalation method to dramatically expand interlayer spacing in FeSe superconductors, surpassing previous records.

Findings

Interlayer spacing up to 55.7 Å achieved

Superconducting transition temperature remains at ~42 K

New class of intercalated superconductors synthesized

Abstract

New superconductors, Li$_x$(C$_n$H$_{2n+3}$N)$_y$Fe$_{1-z}$Se ($n$ = 6, 8, 18), have been synthesized via the co-intercalation of linear monoamines together with Li into FeSe. The distance between neighboring Fe layers expands up to 55.7 {\AA} for n = 18, which is much larger than the previous record of 19 {\AA} in the FeSe-based intercalation superconductors. Tc remains saturated at $\sim$42 K.