Resistivity anisotropy and charge density wave in 2H-NbSe_2 and 2H-TaSe_2

摘要

The in-plane and out-of-plane resistivities of both 2H-TaSe_2 and 2H-NbSe_2 were determined down to 10 K. For both compounds, the resistivity anisotropy shows notably a slope change at temperatures where a CDW transition is expected to occur. On the other hand, for both compounds the resistivity anisotropy at the lowest temperature of measurement is much greater than expected by the LawrenceDoniach model, which relates the critical magnetic field anisotropy to the normal state resistivity anisotropy for 3D-anisotropic superconductors.