Length-dependent oscillations of the conductance through atomic chains: The importance of electronic correlations

– We calculate the conductance of atomic chains as a function of their length. Using the Density Matrix Renormalization Group algorithm for a many-body model which takes into account electron-electron interactions and the shape of the contacts between the chain and the leads, we show that length-dependent oscillations of the conductance whose period depends on the electron density in the chain can result from electron-electron scattering alone. The amplitude of these oscillations can increase with the length of the chain, in contrast to the result from approaches which neglect the interactions. Quantum wires of atomic dimension are among the basic components of molecular electronics. The knowledge of the transport properties of such structures will be crucial for the design of devices, and the understanding of their properties is a major challenge in nanoelectronics. Experimentally, chains of atoms between two electrodes have been formed and investigated [1–3], and the conductance of molecules like H2 has been measured [4]. Besides the possible applications in molecular devices, this is of great general interest since electronic correlations alter considerably the properties of one-dimensional systems. Fermi liquid theory completely looses its applicability and Luttinger liquid [5] behavior appears. This has been observed for the case of metallic single wall carbon nanotubes [6]. A recent measurement on atomic Au, Pt and Ir wires between break junction contacts [7] has revealed oscillations of the conductance as a function of the length of the chain. For an odd number of atoms in the atomic wire the conductance has maxima while it is reduced when the number of atoms is even. This behavior is obtained after averaging over many realizations of the experiment in which the precise form of the contacts between the electrodes and the atomic chain might be different. Since a few years, the conductance of chains of atoms has been the subject of an increasing theoretical activity (see Sect. 11.5.1 of Ref. [3] for an overview), and parity-oscillations had