Abstract
We study the electronic correlation e ects in armchair graphene nanoribbons that have been recently proposed to be the building blocks of spin qubits. The armchair edges give rise to peculiar quantum interferences and lead to quenched kinetic energy of the itinerant carriers at appropriate doping level. This is a beautiful one-dimensional analogy of the Landau level formation in two dimensions except the magnetic eld is not needed here. Combining the techniques of e ective eld theory and variational wave function approach, we found that the ground state exhibits a new type of at-band ferromagnetism that hasn't been found before. At the end, we address practical issues about realization of this novel magnetic state in experiments.