Two pressure-induced transitions in TiOCl: Mott insulator to anisotropic metal

Abstract

Using Car-Parrinello molecular dynamics calculations we investigate the behavior of the low-dimensional multiorbital Mott insulator TiOCl under pressure. We show that the system undergoes {\it two} consecutive phase transitions, first at $P_{\text{c}}$ from a Mott-insulator to a metallic phase in the $ab$ plane with a strong Ti-Ti dimerization along $b$. At a pressure $P_{\text{c}}^{\prime }>P_{\text{c}}$ the dimerization disappears and the system behaves as a uniform metal. This second transition has not yet been reported experimentally. We show that the insulator-to-metal transition at $P_{\text{c}}$ is driven by the widening of the bandwidth rather than structural changes or reduction of crystal field splittings and it shows a redistribution of the electronic occupation within the $t_{2g}$ bands. Our computed pressure-dependent lattice parameters are consistent with experimental observations and the existing controversy on the change of crystal symmetry at high pressures is discussed.

4 pages, 4 figures, accepted in PRL

References in corpus (3)

• Mott Transition from a Spin Liquid to a Fermi Liquid in the Spin-Frustrated Organic Conductor kappa-(ET)2Cu2(CN)3
• Incommensurate interactions and non-conventional spin-Peierls transition in TiOBr
• Unusual quasi-one-dimensional electron dispersions in the spin-1/2 quantum magnet TiOCl

Cited by in corpus (4)

• Microscopic origin of pressure-induced phase transitions in iron-pnictide $AF{e}_{2}A{s}_2$ superconductors: an {ab initio} molecular-dynamics study
• Proximity of LaOFeAs to a magnetic instability
• Microscopic model for transitions from Mott to spin-Peierls insulator in TiOCl
• Momentum-resolved single-particle spectral function for TiOCl from a combination of density functional and variational cluster calculations