The Synthesis and Superconducting Behavior of Crystalline Superlattices: (TiSe2)m(NbSe2)n

Abstract

AbstractA series of kinetically stable, crystalline superlattices containing an integral number of intergrown TiSe2 and NbSe2 layers have been synthesized by controlled crystallization of elementally modulated reactants. Theta-theta and rocking curve data were collected to study the evolution of the initially layered reactants into the crystalline superlattices as a function of temperature. Nucleation of the dichalcogenide structure occurs upon annealing at temperatures above 200°C with the c-axis oriented perpendicular to the substrate surface. The [00l] diffraction linewidths decrease with increased annealing time and temperature suggesting growth of the c-axis domain size. High quality c-axis oriented dichalcogenide crystalline superlattices result from extended annealing at the relatively low annealing temperature of 500°C. The large number of well resolved [00l] Bragg diffraction peaks confirm the well developed crystal structure of the product superlattices in this direction. Four probe electrical conductivity measurements were used to determine the variation of the superconducting critical temperature as a function of the number of TiSe2 and NbSe2 layers in the superlattice.