Anomalous mass enhancement in strongly-correlated quantum wells

Using dynamical-mean-field theory, we investigate the electronic properties of quantum wells consisting of a $t^1_{2g}$-electron system with strong correlations. The special focus is on the subband structure of such quantum wells. The effective mass is found to increase with increase in the value of the bottom of the subband, i.e., decrease in the subband occupation number. This is due to the combination of Coulomb repulsion, whose effect is enhanced on surface layers, and longer-range hoppings. We discuss the implication of these results for the recent angle-resolved photoemission experiment on SrVO$_3$ thin films.