  We report on the observation of magnetoresistance oscillations in graphene
p-n junctions. The oscillations have been observed for six samples, consisting
of single-layer and bilayer graphene, and persist up to temperatures of 30 K,
where standard Shubnikov-de Haas oscillations are no longer discernible. The
oscillatory magnetoresistance can be reproduced by tight-binding simulations.
We attribute this phenomenon to the modulated densities of states in the n- and
p- regions.
