Direct evidence of magnetic correlations deep inside the superconducting state of CaFe1.94Co0.06As2

TL;DR

This study provides direct evidence of magnetic correlations coexisting with superconductivity deep inside the superconducting state of CaFe1.94Co0.06As2, revealing complex phase interactions and spatial coexistence.

Contribution

It demonstrates the coexistence of magnetic correlations and superconductivity within the same phase in CaFe1.94Co0.06As2 using local magnetic field imaging.

Findings

Magnetic correlations are present within Meissner-like regions.

Magnetic phase shrinks as superconducting phase grows with decreasing temperature.

Coexistence of magnetic and superconducting phases persists deep inside the superconducting state.

Abstract

Imaging local magnetic field distribution in a single crystal of superconductor CaFe1.94Co0.06As2 shows the presence of anomalous remnant magnetization within Meissner like regions of the sample. Close to the superconducting transition temperature we find a coexistence of superconductivity and magnetic correlations. While the magnetic correlations are enhanced with the lowering of temperature, interestingly the area over which the magnetic phase exists shrinks at the expense of a growing superconducting phase in the sample. The coexistence of two phases deep inside the superconducting phase in this compound is maintained within the temperature range that we have explored in our experiment.