Reduced dimensionality and pseudogap formation in (LaMnO$_{3}$)$_{2n}$(SrMnO$_{3}$)$_{n}$ superlattices

(LaMnO$_{3}$)$_{2n}$(SrMnO$_{3}$)$_{n}$ superlattices, composed of the antiferromagnetic insulators LaMnO$_{3}$ (LMO) and SrMnO$_{3}$ (SMO), are ferromagnetic and metallic for n $<$ 3. By increasing the separation between LMO/SMO interfaces for n $\ge$ 3, the system goes through a transition from a metallic to insulating ground state whose origin remains unresolved. We present ARPES measurements of LMO$_{2n}$SMO$_{n}$ superlattices grown by MBE. The electronic structure of states near the Fermi level is similar to the random alloy La$_{2/3}$Sr$_{1/3}$MnO$_{3}$ for small n, but as n is increased we observe the formation of a more 2D state with a preferential occupation of $x^2-y^2$ orbitals. As the system passes into the insulating state at n = 3, a pseudogap forms at the Fermi level: charge carriers are suppressed over a scale of hundreds of meV but without substantial changes to the overall bandstructure. This pseudogap begins to fill as the temperature is increased, but a large suppression in spectral weight at the Fermi level remains at room temperature. Our observations indicate that the insulating state for large-n superlattices is related to strong many-body effects within this system, enhanced by the reduced dimensionality of an interfacial two-dimensional electron liquid.