Quantum properties of atomic-sized conductors

Abstract

Using remarkably simple experimental techniques it is possible to gently break a metallic contact and thus form conducting nanowires. During the last stages of the pulling a neck-shaped wire connects the two electrodes, the diameter of which is reduced to single atom upon further stretching. For some metals it is even possible to form a chain of individual atoms in this fashion. Although the atomic structure of contacts can be quite complicated, as soon as the weakest point is reduced to just a single atom the complexity is removed. The properties of the contact are then dominantly determined by the nature of this atom. This has allowed for quantitative comparison of theory and experiment for many properties, and atomic contacts have proven to form a rich test-bed for concepts from mesoscopic physics. Properties investigated include multiple Andreev reflection, shot noise, conductance quantization, conductance fluctuations, and dynamical Coulomb blockade. In addition, pronounced quantum effects show up in the mechanical properties of the contacts, as seen in the force and cohesion energy of the nanowires. We review this reseach, which has been performed mainly during the past decade, and we discuss the results in the context of related developments.Comment: Review, 120 pages, 98 figures. In view of the file size figures have been compressed. A higher-resolution version can be found at: http://lions1.leidenuniv.nl/wwwhome/ruitenbe/review/QPASC-hr-ps-v2.zip (5.6MB zip PostScript

Fabrication of stable metal nanowire showing conductance quantization in solution

“…Well-defined peaks are generally observed near 1, 2, and 3 G 0 in the conductance histogram for Au. In the case of Cu and Ag, the conductance histograms have a dominant peak at 1 G 0 [1]. While the quantized conductance behavior is similar among noble metals, the structure of the nanowire depends on the metals.…”

“…Recently, metal nanowires on an atomic scale have been fabricated with a scanning tunneling microscope (STM) and mechanically controllable break junctions (MCBJ) [1].…”

“…Electrical conductance through the metal nanowire is expressed by where T 2 i is the transmission probability of the i-th conductance channel, e is the electron charge, and h is Plank's constant [1]. The value of is a unit of the quantized conductance.…”

Quantized conductance behavior of Pt metal nanoconstrictions under electrochemical potential control

“…In recent years, metal nanoconstrictions have attracted attention for interest of fundamental science as well as expectation of applications for nano devices [1,2]. The electrical conductance through an atomic scale metal nanoconstriction is expressed by G = (2e 2 / h)ΣT i , where T i is the transmission probability of the i-th conductance channel, e is the electron charge, h is Planck's constant, and G 0 = 2e 2 /h is a unit of quantum conductance [1].…”

“…The electrical conductance through an atomic scale metal nanoconstriction is expressed by G = (2e 2 / h)ΣT i , where T i is the transmission probability of the i-th conductance channel, e is the electron charge, h is Planck's constant, and G 0 = 2e 2 /h is a unit of quantum conductance [1]. Various quantized conductance behavior has been observed for metal nanoconstrictions fabricated using a scanning tunneling microscope (STM) and mechanically controllable break junctions (MCBJ) technique.…”