Quantization of persistent currents in quantum dot at strong magnetic fields

We investigate equilibrium electron currents and magnetization in an ideal two-dimensional disc of radius R placed in a strong magnetic field H. The most striking results emerge when the conditions for the existence of edge and bulk states are met, namely RaH = (h̵c/eH)12. When the Fermi energy is locked on a Landau level, the current as a function of electron density is quantized in units of (eh)(h̵ωc/2), where ωc is the cyclotron frequency. We argue that this effect survives against weak disorder. It is also shown that the persistent current has an approximately periodic dependence on 1/H.