Variations in the Conductive and Superconductive Properties of {[TiSe2]l[NbSe2]m}nSuperlattices as a Function of Superlattice Structure

Abstract

An extensive set of {[TiSe2]l[NbSe2]m}n superlattices has been prepared through controlled annealing of elementally modulated reactants. Electrical conductances were measured from 1.5 K to room temperature. The room temperature conductances are linearly dependent on the number (m) of NbSe2 layers per repeat layer, and independent of the number (l) of semimetallic TiSe2 layers per repeat layer, suggesting that the electronic transport is dominated by the metallic NbSe2 layers. For small l, a positive temperature coefficient of resistance (TCR) is observed, indicative of normal metallic behavior. In general, increasing l reduces the TCR, and for smaller m, the TCR becomes negative at larger l. These samples exhibit a √T temperature dependence to the resistivity variation at low temperatures, characteristic of both weak localization and electron−electron interaction effects for three-dimensional electron flow in strongly disordered systems. Superconducting critical temperatures were also observed to depend s...