We present a comprehensive investigation of the field-dependent critical current density and pinning force, combined with a detailed analysis of the nanostructural defect landscape in single crystal of underdoped PrFeAs(O,F) superconductor. Our study demonstrates that for both in-plane and out-of-plane magnetic field orientations critical current density exhibits a strong pinning regime in intermediate fields across the entire temperature range. The dominant contribution to pinning originates from oxygen-to-fluorine substitutional defects, oxygen vacancies, which all act as point defects via a quasiparticle mean free path fluctuation mechanism. Scanning transmission electron microscope studies did not reveal any volume or surface defect types within the lattice.
@article{arxiv.2510.10264,
title = {Vortex matter and strong pinning in underdoped PrFeAs(O,F) with atomic-sized defects},
author = {Andrey V. Sadakov and Vladimir A. Vlasenko and A. Yu. Levakhova and I. V. Zhuvagin and E. M. Fomina and V. A. Prudkoglyad and A. Y. Tsvetkov and A. S. Usoltsev and N. D. Zhigadlo},
journal= {arXiv preprint arXiv:2510.10264},
year = {2025}
}