Ferroelectricity in Free Niobium Clusters

Abstract

Electric deflections of gas-phase, cryogenically cooled, neutral niobium clusters [NbN; number of atoms (N) = 2 to 150, temperature (T) = 20to 300kelvin], measured in molecular beams, show that cold clusters may attain an anomalous component with very large electric dipole moments. In contrast, room-temperature measurements show normal metallic polarizabilities. Characteristic energies kBTG(N) [Boltzmann constant kB times a transition temperature TG(N)] are identified, below which the ferroelectric-like state develops. Generally, TG decreases [110 > TG(N) > 10K] as N increases, with pronounced even-odd alternations for N > 38. This new state of metallic matter may be related to bulk superconductivity.

Charge expulsion and electric field in superconductors

“…Remarkably, very recently Moro et al reported detection of spontaneous electric dipole moments in Nb clusters [17] at low temperatures. Their observations that the effect is strongest for even number of electrons in the cluster and that it occurs only at low temperatures suggests that the effect is related to superconductivity [17] as proposed by the authors.…”

“…Remarkably, very recently Moro et al reported detection of spontaneous electric dipole moments in Nb clusters [17] at low temperatures. Their observations that the effect is strongest for even number of electrons in the cluster and that it occurs only at low temperatures suggests that the effect is related to superconductivity [17] as proposed by the authors. Moro et al concluded from their observations the existence of an internal electric field in the interior of the metal cluster of the order of 10 6 V /cm, and stress that such an internal electric field cannot occur in an ordinary metal and suggests a 'rigidity' of the electronic wavefunctions as well as a collective effect.…”

Absolute Ionization Rates of Multielectron Transition Metal Atoms in Strong Infrared Laser Fields

“…For Nb, by contrast, 0:5 represents a very strong dynamic screening effect. This anomalous behavior is currently under further investigation in our laboratory, but several indications of the unusual polarizability of Nb and its clusters have been documented in the literature [21,22].…”

Room-temperature-concerted switch made of a binary atom cluster

“…Furthermore, the present method to construct a size-defined cluster is widely applicable to various elements on several surfaces. Nanoclusters are known to exhibit unique physical and chemical properties that depend strongly on their size and constituent atoms [42][43][44][45][46] . This motivates us to create a variety of atomic-scale devices with different functionalities and to systematically embed them into desired nanoregions, which opens up novel nanofabrication to achieve atomic-scale integrated electronics for RT operation.…”