The thermodynamic properties of graphene nanoribbons under zero and finite magnetic fields have
been investigated. We have obtained qualitative and quantitative results of the free energy and the
magnetic susceptibility in graphene nanoribbons. The electronic states in the tight-binding
approximation were used to calculate the thermal and magnetic properties. In the case of a finite
magnetic field, the Harper equation was solved for the electronic state for various wavevectors.The
magnetic field and temperature dependence of the magnetic susceptibility over a wide field and
temperature range are presented.