Magnetic response in one-dimensional mesoscopic rings: Long-range hopping in shortest path

Persistent current and low-field magnetic susceptibility in single-channel normal metal rings threaded by a magnetic flux φ are investigated within the tight-binding framework considering long-range hopping of electrons in the shortest path. The higher order hopping integrals try to reduce the effect of disorder by delocalizing the energy eigenstates, and accordingly, current amplitude in disordered rings becomes comparable to that of an ordered ring. Our study of low-field magnetic susceptibility predicts that the sign of persistent currents can be mentioned precisely in mesoscopic rings with fixed number of electrons, even in the presence of impurity in the rings. For perfect rings, low-field current shows only the diamagnetic sign irrespective of the total number of electrons Ne. On the other hand, in disordered rings it exhibits the diamagnetic and paramagnetic natures for the rings with odd and even Ne respectively. PACS No.: 73.23.Ra; 73.23.-b; 71.23.-k; 73.20.Jc; 75.20.-g