Upper critical field of 2H‐NbSe2: Effect of Ga–intercalation

The layered compound of 2H‐NbSe2 and its derivatives (2H‐Ga0.05NbSe2 and 2H‐Ga0.10NbSe2) are prepared by the reaction of elements. From low temperature resistivity measurement, the superconducting transition temperature ‘Ts’ was noticed at 7.4 K in 2H‐NbSe2, which decreases in the case of Ga‐intercalated compounds. We have noticed significant positive magnetoresistance above transition temperature by applying external magnetic field perpendicular to layer for pure single crystal. Single crystal of 2H‐NbSe2 showed anisotropic behavior in upper critical field and we have calculated it ∼3 around t = 0.81, where t = T/Ts. However the upper critical fields for poly crystalline compounds are different from each other.