Kronig-Penney model of scalar and vector potentials in graphene

We consider a one-dimensional (1D) superlattice (SL) on graphene consisting of very high and very thin (δ-function) magnetic and potential barriers with zero average potential and zero magnetic field. We calculate the energy spectrum analytically, study it in different limiting cases, and determine the condition under which an electron beam incident on an SL is highly collimated along its direction. In the absence of the magnetic SL the collimation is very sensitive to the value of W/W(s) and is optimal for W/W(s) = 1, where W is the distance between the positive and negative barriers and L = W + W(s) is the size of the unit cell. In the presence of only the magnetic SL the collimation decreases and the symmetry of the spectrum around k(y) is broken for W/W(s) ≠ 1. In addition, a gap opens which depends on the strength of the magnetic field. We also investigate the effect of spatially separated potential and magnetic δ-function barriers and predict a better collimation in specific cases.