Titanium Nitride - a correlated metal at the threshold of a Mott transition

TL;DR

This paper explores the electron correlation effects in Titanium Nitride, revealing its proximity to a Mott transition and explaining the pseudogap phenomenon through advanced many-body calculations.

Contribution

It combines electronic structure and many-body methods to analyze TiN, providing new insights into its correlated metallic state near a Mott transition.

Findings

Electronic correlations are crucial in TiN.

The pseudogap is explained by proximity to a Mott transition.

Results align with spectroscopy data.

Abstract

We investigate electron correlation effects in stoichiometric Titanium Nitride (TiN) using a combination of electronic structure and many-body calculations. In a first step, the Nth-order muffin tin orbital technique is used to obtain parameters for the low-energy Hamiltonian in the Ti-d(t2g)-band manifold. The Coulomb-interaction U and the Hund's rule exchange parameter J are estimated using a constrained Local-Density-Approximation calculation. Finally, the many-body problem is solved within the framework of the Variational Cluster Approach. Comparison of our calculations with different spectroscopy results stresses the importance of electronic correlation in this material. In particular, our results naturally explain a suppression of the TiN density of states at the Fermi level (pseudogap) in terms of the proximity to a Mott metal-insulator transition.