Experimental evidence for a two-band superconducting state of NbSe2 single crystals

We report on measurements and a detailed analysis of the reversible magnetization of superconducting NbSe2 single crystals. By comparing the experimental data with Ginzburg Landau theory we show that superconductivity in NbSe2 cannot be explained by an anisotropic single-band but by a multiband scenario. Applying a simple two-band model reveals the basic mixed-state parameters, which are quite different in the two bands. We identify a strongly anisotropic band that determines the properties at high magnetic fields and a second almost isotropic band that dominates at low fields. Our method is well suited for distinguishing anisotropic single-band from multiband superconductivity in various materials.