Ferroelectricity in Free Niobium Clusters

Authors

Ramiro Moro, Georgia Institute of Technology
Xiaoshan Xu, University of Nebraska-LincolnFollow
Shuangye Yin, Georgia Institute of Technology
Walt A. de Heer, Georgia Institute of Technology

Document Type

Article

Date of this Version

2003

Citation

SCIENCE VOL 300 23 MAY 2003

Comments

Used by permission.

Abstract

Electric deflections of gas-phase, cryogenically cooled, neutral niobium clusters [Nb_N; number of atoms (N) = 2 to 150, temperature (T) = 20 to 300 kelvin], 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 k_BT_G(N) [Boltzmann constant k_B times a transition temperature T_G(N)] are identified, below which the ferroelectric-like state develops. Generally, T_G decreases [110 > T_G(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.