Direct Observation of Vortex and Meissner Domains in a Ferromagnetic Superconductor EuFe2(As0.79P0.21)2 Single Crystal

Abstract

A spontaneous vortex structure in magnetic domains (vortex domains) has been visualized by the decoration technique near the ferromagnetic transition temperature (TC = 18 K) in a ferromagnetic superconductor EuFe2(As0.79P0.21)2 single crystal with the superconducting transition temperature (TSC = 22 K). Meissner domains previously observed by magnetic force microscopy have also been observed in a narrow temperature range (ΔT ∼ 1 K) near TC. A domain structure with the alternating direction of the magnetic flux has been observed upon cooling below TC. Experimental results are in reasonable agreement with a theoretical estimate of the periods of domain structures and the temperature interval below TC in which they are observed.