# Extreme anisotropy and anomalous transport properties of heavily electron doped Lix(NH3)yFe2Se2 single crystals

## TL;DR

This study reports on heavily electron doped Li-NH3 intercalated FeSe single crystals exhibiting extreme electronic anisotropy and anomalous transport properties, offering insights into the superconductivity mechanism in FeSe-based materials.

## Contribution

The paper introduces a new, simplified material platform of Li-NH3 intercalated FeSe crystals to study intrinsic superconducting properties free from structural complexities.

## Key findings

- Large electronic anisotropy in normal and superconducting states
- Anomalous transport properties related to anisotropic relaxation time
- Insights into superconductivity origin in FeSe-related superconductors

## Abstract

The missing hole packets near the Brillouin zone center render unique electronic structures to the heavily electron doped FeSe-based superconductors with Tc above 40 K. It challenges the existing scenario accounting for the nature of superconductivity in the iron-based family. Yet, one hurdle that has to be overcome is the materials complexity in the rather limited number of compounds. Here we report the growth of heavily electron doped Li-NH3 intercalated FeSe single crystals that are free of such complexities and allow access to the intrinsic superconducting properties. Our results show extremely large electronic anisotropy in both normal and superconducting states. Moreover, the anomalous transport properties appear in normal state, which are believed related to the anisotropy of relaxation time and/or temperature dependent electron carrier concentration. In view of the great chemical flexibility of intercalants, our findings provide novel platform to understanding of superconductivity origin of FeSe-related superconductors.