“…To give a sample, Harper [25] used the tight-binding model (discrete Laplacian) to describe the effect of the magnetic field on conduction (see also [30]). In mathematical literature, discrete magnetic Schrödinger operator was introduced by Lieb and Loss [34] and Sunada [45,46], and studied, among other sources, in [41,15,16] (see also [47] for a review).…”