Temperature dependences of the magnetic moment have been measured in YBa_2Cu_3O_{7-\delta} thin films over a wide magnetic field range (5 <= H <= 10^4 Oe). In these films a paramagnetic signal known as the paramagnetic Meissner effect has been observed. The experimental data in the films, which have strong pinning and high critical current densities (J_c ~ 2 \times 10^6 A/cm^2 at 77 K), are quantitatively shown to be highly consistent with the theoretical model proposed by Koshelev and Larkin [Phys. Rev. B 52, 13559 (1995)]. This finding indicates that the origin of the paramagnetic effect is ultimately associated with nucleation and inhomogeneous spatial redistribution of magnetic vortices in a sample which is cooled down in a magnetic field. It is also shown that the distribution of vortices is extremely sensitive to the interplay of film properties and the real experimental conditions of the measurements.
@article{arxiv.cond-mat/0306690,
title = {The origin of paramagnetic magnetization in field-cooled YBa2Cu3O7 films},
author = {D. A. Luzhbin and A. V. Pan and V. A. Komashko and V. S. Flis and V. M. Pan and S. X. Dou and P. Esquinazi},
journal= {arXiv preprint arXiv:cond-mat/0306690},
year = {2007}
}