Nanometer scale electronic reconstruction at the interface between LaVO3 and LaVO4

Electrons at interfaces, driven to minimize their free energy, are distributed differently than in bulk. This can be dramatic at interfaces involving heterovalent compounds. Here we profile an abrupt interface between V 3d(2) LaVO3 and V 3d(0) LaVO4 using electron energy loss spectroscopy. Although no bulk phase of LaVOx with a V 3d(1) configuration exists, we find a nanometer-wide region of V 3d(1) at the LaVO3/LaVO4 interface, rather than a mixture of V 3d(0) and V 3d(2). The two-dimensional sheet of 3d(1) electrons is a prototypical electronic reconstruction at an interface between competing ground states.