Half-metallic semiDirac point generated by quantum confinement in TiO$_2$/VO$_2$ nanostructures

TL;DR

This study reveals that quantum confinement in VO$_2$/TiO$_2$ nanostructures creates a novel semiDirac point state with unique electronic properties, combining massless and massive charge carriers in a two-dimensional system.

Contribution

It introduces a new semiDirac point state in confined VO$_2$ within TiO$_2$, demonstrating a novel electronic phase induced by quantum confinement.

Findings

Formation of a semiDirac point in nanostructures.

Charge carriers are massless along one axis and massive along another.

Effects of interface imperfections are analyzed.

Abstract

Multilayer VO$_2$/TiO$_2$ nanostructures ($d^1$ - $d^0$ interfaces with no polar discontinuity) are studied with first principles density functional methods including structural relaxation. Quantum confinement of the {\it half metallic} VO$_2$ slab within insulating TiO$_2$ produces an unexpected and unprecendented two-dimensional new state, with a {\it semiDirac} point Fermi surface: spinless charge carriers are effective-mass like along one principal axis, but are massless along the other. Effects of interface imperfection are addressed.