Preparation of atomically flat TiO$_{2}$(001) surfaces

Transition metal oxides with the rutile structure (MO$_{2}$, M$=$ e.g. Ti, V, or Nb) have highly directional partially occupied t$_{\mathrm{2g}}$ orbitals. Some of these orbitals form quasi-1D electronic bands along the rutile c-axis, and Peierls-like ordering phenomena have been observed in VO$_{2}$ and NbO$_{2}$. Tailoring the electronic properties of these materials \textit{via} quantum confinement requires epitaxial growth on suitable substrates such as low index TiO$_{2}$ surfaces. Because of the high surface energy of rutile TiO$_{2}$(001), the standard approach of sputtering and annealing usually introduces faceting. Here we demonstrate a facile method to create atomically flat, non-faceted TiO$_{2}$(001) surfaces. Using scanning tunneling microscopy we observe terraces with a width of approximately 150 nm. Step heights of approximately 0.3 nm are observed, consistent with the $c$ lattice parameter of rutile TiO$_{2}$. Low energy electron diffraction patterns reveal sharp diffraction spots with an in-plane lattice constant of 0.358 nm which is consistent with a (1x1) ordering of the (001) plane. These TiO$_{2}$(001) single crystal surfaces can serve as an ideal substrate for further growth of rutile heterostructures.