Ultrathin Niobium in the Si/Nb/Si Trilayers
I. Zaytseva a, O. Abal'oshev a, P. Dłużewski a, R. Minikayev a, Marta Z. Cieplak a, L.Y. Zhu b and C.L. Chien b
aInstitute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
bDepartment of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
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We study magnetotransport properties of the Si/Nb/Si trilayers, in which the thickness of niobium, d, changes from 1.1 nm to 50 nm, while the thickness of Si is fixed at 10 nm. The niobium films are amorphous for d < 4 nm, while in thicker films the alligned polycrystalline grains are formed. We observe that the Hall coefficient changes sign into negative in the films with d < 1.6 nm. We also find that in the ultrathin films the magnetic field induces a transition from the superconducting into a metallic phase with the resistance smaller than the normal-state resistance.

DOI: 10.12693/APhysPolA.126.A-140
PACS numbers: 74.78.-w, 74.70.Ad, 74.25.-q