We employ density functional theory plus dynamical mean field theory and identify the physical origin of why two layers of ${\mathrm{SrVO}}_3$ on a ${\mathrm{SrTiO}}_3$ substrate are insulating: the thin film geometry lifts the orbital degeneracy, which in turn triggers a first-order Mott-Hubbard transition. Two layers of ${\mathrm{SrVO}}_3$ are just at the verge of a Mott-Hubbard transition and hence ideally suited for technological applications of the Mott-Hubbard transition: the heterostructure is highly sensitive to strain, electric field, and temperature. A gate voltage can also switch between metal (on) and insulator (off), so that a transistor with ideal on-off switching properties is realized.

• Received 20 December 2013

DOI:https://doi.org/10.1103/PhysRevLett.114.246401