Transport properties and the anisotropy of Ba_{1-x}K_xFe_2As_2 single crystals in normal and superconducting states

TL;DR

This study investigates the transport and superconducting properties of Ba_{1-x}K_xFe_2As_2 single crystals, revealing significant resistivity anisotropy likely caused by extrinsic defects, with implications for understanding their anisotropic electronic behavior.

Contribution

It provides new insights into the anisotropic transport properties and the extrinsic factors affecting resistivity in Ba_{1-x}K_xFe_2As_2 superconductors.

Findings

Resistivity anisotropy b3 is temperature independent and ranges from 10 to 30.

Out-of-plane resistivity varies significantly between samples, indicating extrinsic effects.

Presence of flat defects along Fe-As layers influences resistivity anisotropy.

Abstract

The transport and superconducting properties of Ba_{1-x}K_xFe_2As_2 single crystals with T_c = 31 K were studied. Both in-plane and out-of plane resistivity was measured by modified Montgomery method. The in-plane resistivity for all studied samples, obtained in the course of the same synthesis, is almost the same, unlike to the out-of plane resistivity, which differ considerably. We have found that the resistivity anisotropy \gamma=\rho_c /\rho_{ab} is almost temperature independent and lies in the range 10-30 for different samples. This, probably, indicates on the extrinsic nature of high out-of-plane resistivity, which may appear due to the presence of the flat defects along Fe-As layers in the samples. This statement is supported by comparatively small effective mass anisotropy, obtained from the upper critical field measurements, and from the observation of the so-called "Friedel transition", which indicates on the existence of some disorder in the samples in c-direction.