Eur. Phys. J. D 27, 43-53 (2003)
https://doi.org/10.1140/epjd/e2003-00234-2

Orbital magnetism in axially deformed sodium clusters

From scissors mode to dia-para magnetic anisotropy

¹ Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region 141980, Russia
² Technische Universität Dresden, Institut für Analysis, 01062 Dresden, Germany
³ Institut für Theoretische Physik, Universität Erlangen, 91058 Erlangen, Germany
⁴ Dipartimento di Scienze Fisiche, Università di Napoli “Federico II” and Istituto Nazionale di Fisica Nucleare, Dipartamento di Scienze Fisiche, Monte S. Angelo, Via Cinthia, 80126 Napoli, Italy
⁵ Departamento de Fisica, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil

Corresponding author: ^a nester@thsun1.jinr.ru

Received: 20 December 2002
Published online: 29 July 2003

Abstract

Low-energy orbital magnetic dipole excitations, known as the scissors mode (SM), are studied in alkali metal clusters. Subsequent dynamic and static effects are explored. The treatment is based on a self-consistent microscopic approach using the jellium approximation for the ionic background and the Kohn-Sham mean field for the electrons. The microscopic origin of SM and its main features (structure of the mode in light and medium clusters, separation into low- and high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole plasmons, contributions of shape isomers, etc.) are discussed. It is shown that the scissors M1 strength acquires large values with increasing cluster size. The mode is responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum shell effects induce a fragile interplay between Langevin diamagnetism and van Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic susceptibility of particular light clusters. Finally, several routes for observing the SM experimentally are discussed.