title: 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.
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta GA, 30332-0430, USA.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Moro
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Xu
authors.forename: Shuangye
authors.initials: S
authors.lastname: Yin
authors.forename: Walt A
authors.initials: WA
authors.lastname: de Heer