Direct Observation of Pinning of Abrikosov Vortices in a Specially Inhomogenious Crystal EuRbFe4As4.

In the two-phase crystal EuRbFe4As4/EuFe2As2 (1144/122), a linear ordering of Abrikosov vortices, uncharacteristic for superconducting pnictides, has been found using the method of decorating with magnetic nanoparticles. The observed chains of vortices directed along crystallographic 〈110〉 axes of the orthorhombic EuFe2As2 phase are explained by pinning of vortices in the superconducting phase 1144 on linear defects associated with the twin boundaries of the non-superconducting 122 phase. [ABSTRACT FROM AUTHOR]