Fishtail effect and the vortex phase diagram of single crystal Ba0.6K0.4Fe2As2

TL;DR

This study investigates the vortex phase diagram of Ba0.6K0.4Fe2As2 single crystals, revealing the fishtail effect, high critical fields, and strong vortex pinning, indicating promising superconducting applications.

Contribution

First comprehensive vortex phase diagram of Ba0.6K0.4Fe2As2, highlighting the fishtail effect and vortex pinning mechanisms.

Findings

Fishtail effect observed in magnetization loops

Maximum vortex pinning force at 1/3 reduced field

High upper critical field and large current capacity

Abstract

By measuring the magnetization hysteresis loops of superconducting Ba0.6K0.4Fe2As2 single crystals, we obtained the high upper critical field and large current carrying ability, which point to optimistic applications. The fishtail (or second peak) effect is also found in the material, and the position of the vortex pinning force shows a maximum at 1/3 of the reduced field, being consistent with the picture of vortex pinning by small size normal cores in the sample. Together with the resistive measurements, for the first time the vortex phase diagram is obtained for superconductor Ba0.6K0.4Fe2As2.