INDUCED QUANTUM NUMBERS IN A (2-DIMENSIONAL ELECTRON-GAS(1))

A gas of electrons confined to a plane is examined in both the relativ istic and nonrelativistic case. Using a (0+1)-dimensional effective th eory, a remarkably simple method is proposed to calculate the spin den sity induced by a uniform magnetic background field. The physical prop erties of possible fluxon excitations are determined. It is found that while in the relativistic case they can be considered as half-fermion s (semions) in that they carry half a fermion charge and half the spin of a fermion, in the nonrelativistic case they should be thought of a s fermions, having the charge and spin of a fermion.