Self-trapping of electrons by vortices F. V. Kusmartsev, K.-U. Neumann, O. Schärpf and K. R.A. Ziebeck Europhys. Lett., 42 5 (1998) 547-552 Published online: 01 September 2002 DOI: 10.1209/epl/i1998-00286-8