Persistent currents and spin-charge separation in a one-dimensional Hubbard ring with side sites

Abstract

The persistent current and spin-charge separation are studied in a one-dimensional ͑1D͒ Hubbard ring with side sites connected to the even sites of the ring. At half filling, the persistent current is always paramagnetic and has a period of flux quantum. Away from half filling, as the onsite repulsion U increases, the sign of the current may oscillate depending on the total number of electrons N e and the hopping t between the ring site and the side site. For small hopping t, the number of electrons N e