Europhys. Lett.
Volume 63, Number 6, September 2003
Page(s) 846 - 852
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 November 2003
DOI: 10.1209/epl/i2003-00604-2
Europhys. Lett., 63 (6) , pp. 846-852 (2003)

Fractional periodicity of persistent currents: A signature of broken internal symmetry

P. Singha Deo1, P. Koskinen2, M. Koskinen2 and M. Manninen2

1  S. N. Bose National Centre for Basic Sciences, JD Block, Sector III Salt Lake City, Kolkata 98, India
2  Department of Physics, University of Jyväskylä - FIN-40351 Jyväskylä, Finland

(Received 22 October 2002; accepted in final form 10 July 2003)

We show from the symmetries of the many-body Hamiltonian, cast into the form of the Heisenberg (spin) Hamiltonian, that the fractional periodicities of persistent currents are due to the breakdown of internal symmetry and the spin Hamiltonian holds the explanation to this transition. Numerical diagonalizations are performed to show this explicitly. Persistent currents therefore, provide an easy way to experimentally verify broken internal symmetry in electronic systems.

67.40.Db - Quantum statistical theory; ground state, elementary excitations.
73.21.La - Quantum dots.

© EDP Sciences 2003