Coexistence of Light and Heavy Carriers Associated with Superconductivity and Antiferromagnetism in CeNi0.8Bi2 with a Bi Square Net

We found that the ZrCuSiAs-type crystal CeNi0.8Bi2 with a layered structure composed of alternate stacking of [CeNixBi(1)](delta+) and Bi(2)(delta-) exhibits a superconductive transition at similar to 4 K. The conductivities, magnetic susceptibilities, and heat capacities measurements indicate the presence of two types of carriers with notable different masses, i.e., a light electron responsible for superconductivity and a heavy electron interacting with the Ce 4f electron. This observation suggests that 6p electrons of Bi(2) forming the square net and electrons in CeNixBi(1) layers primarily correspond to the light and heavy electrons, respectively.