@article {37097,
	title = {Influence of randomly distributed magnetic nanoparticles on surface superconductivity in Nb films},
	journal = {PHYSICAL REVIEW B},
	volume = {70},
	year = {2004},
	month = {2004},
	abstract = {We report on combined resistance and magnetic measurements in a hybrid structure (HS) of randomly distributed anisotropic CoPt magnetic nanoparticles (MN) embedded in a 160 nm Nb thick film. Our resistance measurements exhibited a sharp increase at the magnetically determined bulk upper-critical fields H-c2(T). Above these points the resistance curves are rounded, attaining the normal state value at much higher fields identified as the surface superconductivity fields H-c3(T). When plotted in reduced temperature units, the characteristic field lines H-c3(T) of the HS and of a pure Nb film, prepared at exactly the same conditions, coincide for H<10 kOe, while for fields H>10 kOe they strongly segregate. Interestingly, the characteristic value H=10 kOe is equal to the saturation field H-sat(MN) of the MN. The behavior mentioned above is observed only for the case where the field is normal to the film{\textquoteright}s surface, while it is absent when the field is parallel to the film. Our experimental results suggest that the observed enhancement of surface superconductivity field H-c3(T) is possibly due to the not uniform local reduction of the external magnetic field by the dipolar fields of the MN.},
	isbn = {2469-99502469-9969},
	author = {Stamopoulos, D. and Pissas, M. and Karanasos, V. and Niarchos, D. and Panagiotopoulos, I.}
}
