EXACT-SOLUTIONS FOR BARRIER D-STATES AT HIGH MAGNETIC-FIELDS

Solutions which are exact in the high-magnetic-field limit have recently been reported for a two-dimensional D- problem in which the two electrons and the fixed positive ion are all confined to the x-y plane. The magnetic field is applied in the z direction. We have generalized this model by allowing the fixed positive ion to reside on the z axis at a distance ζ from the x-y plane; the electrons remain confined in that plane. We call this configuration a barrier D- center. Although exactly four bound D- states exist at ζ=0, we find that there are ten different states which, at fixed magnetic field, become bound in various intervals of ζ values; of these states as many as eight can coexist for the barrier D- in certain ranges of ζ. Remarkable changes in the symmetry of the barrier D- ground-state wave function are found, the progression of bound ground states being given by M=0 singlet →M=-1 triplet →M=-2 singlet →M=-3 triplet →M=-5 triplet as ζ increases from zero at fixed magnetic field. (M is the orbital z angular momentum quantum number.) At sufficiently large values of ζ all bound states of the barrier D- center disappear. This progression leads to a predicted magnetic vaporization of barrier D- centers. © 1995 The American Physical Society.