Studies are reported of the upper critical fields of Nb0.53Ti0.47-Ge multilayers consisting of thick Ge layers and varying-thickness Nb0.53Ti0.47 layers. Both the angular dependence and the temperature dependence of the upper critical fields indicate a dimensional crossover at a Nb0.53Ti0.47 layer thickness near 200 Å. All the 2D samples display a cusplike upper critical field angular dependence with a sharper cusp for thinner Nb0.53Ti0.47 layers. The parallel upper critical fields are tentatively fitted with an expression combining the 2D field dependence of Rickayzen, the paramagnetic limiting behavior of Maki, and the disorder-related Coulomb interaction effects of Maekawa and Fukuyama. The perpendicular fields are fitted with the Maekawa, Ebisawa, and Fukuyama theory; better agreement is obtained for thinner Nb0.53Ti0.47 sublayers when the paramagnetic limiting effect is included.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Condensed Matter Physics