The competition between collective quantum phases in materials with strongly correlated electrons depends sensitively on the dimensionality of the electron system, which is difficult to control by standard solid-state chemistry. We have fabricated superlattices of the paramagnetic metal LaNiO3 and the wide-gap insulator LaAlO3 with atomically precise layer sequences. Using optical ellipsometry and low-energy muon spin rotation, superlattices with LaNiO3 as thin as two unit cells are shown to undergo a sequence of collective metalinsulator and antiferromagnetic transitions as a function of decreasing temperature, whereas samples with thicker LaNiO3 layers remain metallic and paramagnetic at all temperatures. Metal-oxide superlattices thus allow control of the dimensionality and collective phase behavior of correlated-electron systems.
@article{arxiv.1111.3819,
title = {Dimensionality Control of Electronic Phase Transitions in Nickel-Oxide Superlattices},
author = {A. V. Boris and Y. Matiks and E. Benckiser and A. Frano and P. Popovich and V. Hinkov and P. Wochner and M. Castro-Colin and E. Detemple and V. K. Malik and C. Bernhard and T. Prokscha and A. Suter and Z. Salman and E. Morenzoni and G. Cristiani and H. -U. Habermeier and B. Keimer},
journal= {arXiv preprint arXiv:1111.3819},
year = {2011}
}