Hard-materials-surface prediction of one-dimensional electron gas

A new and robust one-dimensional electron gas (1DEG) is predicted on the (0 0 1̄) surface of κ-Al2O3 by means of a density-functional-theory (DFT) study. Our first-principles calculations show that this surface is Al terminated, with the Al atoms lying in [1 0 0] zigzag lines, and has an excess of electrons due to the charge asymmetry in the bulk κ-Al2O3. The κ-Al2O3 phase itself is metastable up to 1000 K. To test the robustness of our materials-theory prediction of the 1DEG along the zigzag Al lines, the critical temperature due to a Peierls metal–insulator instability has been estimated to be in the temperature range [0,1] K, using a tight-binding model, where the model parameters are determined with additional DFT calculations. The virtues of both the materials-theory design and the possible 1DEG realization are also discussed.