Mott-Hubbard gap closure and structural phase transition in the oxyhalides TiOBr and TiOCl under pressure

Abstract

Pressure-dependent transmittance and reflectance spectra of TiOBr and TiOCl single crystals at room temperature suggest the closure of the Mott-Hubbard gap, i.e., the gap is filled with additional electronic states extending down to the far-infrared range. According to pressure-dependent x-ray powder diffraction data the gap closure coincides with a structural phase transition. The transition in TiOBr occurs at slightly lower pressure ($p$=14 GPa) compared to TiOCl ($p$=16 GPa) under hydrostatic conditions, which is discussed in terms of the chemical pressure effect. The results of pressure-dependent transmittance measurements on TiOBr at low temperatures reveal similar effects at 23 K, where the compound is in the spin-Peierls phase at ambient pressure.

11 pages, 12 figures; to appear in Phys. Rev. B

References in corpus (10)

• Evidence of a pressure-induced metallization process in monoclinic VO${}_2$
• Correlated metallic state of vanadium dioxide
• Spin-Peierls transition in TiOCl
• Quasiparticles at the verge of localization near the Mott metal-insulator transition in a two-dimensional material
• Zero-field incommensurate spin-Peierls phase with interchain frustration in TiOCl
• Incommensurate interactions and non-conventional spin-Peierls transition in TiOBr
• Pressure-induced insulator-to-metal transition in low-dimensional TiOCl
• Effect of pressure on the polarized infrared optical response of quasi-one-dimensional LaTiO${}_{3.41}$
• One-dimensional versus two-dimensional correlation effects in the oxyhalides TiOCl and TiOBr
• Pressure-induced metallization and structural phase transition of the Mott-Hubbard insulator TiOBr

Cited by in corpus (12)

• Electronic structure of the two-dimensional Heisenberg antiferromagnet VOCl: a multi-orbital Mott insulator
• Two pressure-induced transitions in TiOCl: Mott insulator to anisotropic metal
• Infrared and Terahertz Spectroscopy of Strongly Correlated Electron Systems under Extreme Conditions
• Microscopic model for transitions from Mott to spin-Peierls insulator in TiOCl
• Can the Mott Insulator TiOCl be Metallized by Doping? A First-Principles Study
• Evolution of optical properties of chromium spinels CdCr${}_2$O${}_4$, HgCr${}_2$S${}_4$, and ZnCr${}_2$Se${}_4$ under high pressure
• Momentum-resolved single-particle spectral function for TiOCl from a combination of density functional and variational cluster calculations
• Two pressure-induced structural phase transitions in TiOCl
• Polarization-dependent infrared reflectivity study of Sr${}_{2.5}$Ca${}_{11.5}$Cu${}_{24}$O${}_{41}$ under pressure: Charge dynamics, charge distribution, and anisotropy
• High pressure x-ray study of spin-Peierls physics in the quantum spin chain material TiOCl
• Pressure-driven phase transitions in correlated systems
• Pressure-induced Spin-Peierls to Incommensurate Charge-Density-Wave Transition in the Ground State of TiOCl