MAGNETIC-FIELD EFFECTS ON ANISOTROPIC PARABOLIC QUANTUM DOTS

The many-electron ground states of cylindrical parabolic quantum dots in magnetic fields parallel to the cylindrical axis are investigated b y means of an unrestricted Hartree-Fock method. The many-electron eige nstates are assigned by two quantum numbers, L-z and S-z, the z-compon ents of the total orbital angular momentum and the total spin, respect ively. As the strength of the magnetic field increases, the spin state of the ground state changes from the paramagnetic to the ferromagneti c state according to Hund's rule. \L-z\ of the ground state increases monotonically with magnetic held strength. In the extremely high-held region of complete spin polarization, \L-z\ increases the electron num ber N by N. From the total energy of the ground state, the chemical po tential and the magnetic susceptibility of quantum dots are calculated as functions of electron number up to 12. Magnetic field dependence o f the chemical potential exhibits many cusps, caused by the transition s of many-electron ground states. The chemical potential depends on th e vertical extent of a quasi-two-dimensional dot only in weak and inte rmediate fields where the spin polarization is incomplete, and it depe nds only slightly on the spin Zeeman term for GaAs dots. The magnetic susceptibility for an array of dots consists of two parts, paramagneti c and diamagnetic, and shows oscillation with electron number at low t emperatures.