Study of the pressure effects in TiOCl by ab initio calculations

Abstract

Electronic structure calculations on the low dimensional spin-1/2 compound TiOCl were performed at several pressures in the orthorhombic phase, finding that the structure is quasi-one-dimensional. The Ti3+ (d1) ions have one t2g orbital occupied (dyz) with a large hopping integral along the b direction of the crystal. The most important magnetic coupling is Ti-Ti along the b axis. The transition temperature (Tc) has a linear evolution with pressure, and at about 10 GPa this Tc is close to room temperature, leading to a room temperature spin-Peierls insulator-insulator transition, with an important reduction of the charge gap in agreement with the experiment. On the high-pressure monoclinic phase, TiOCl presents two possible dimerized structures, with a long or short dimerization. Long dimerized state occurs above 15 GPa, and below this pressure the short dimerized structure is the more stable phase.

3 pages, 3 embedded figures, 1 table. A. Piñeiro, et al.,J. Magn. Magn. Mater. (2009) (accepted)

References in corpus (9)

• Spin singlet formation in MgTi${}_2$O${}_4$: evidence of a helical dimerization pattern
• S=1/2 chains and spin-Peierls transition in TiOCl
• Spin-Peierls transition in TiOCl
• Zero-field incommensurate spin-Peierls phase with interchain frustration in TiOCl
• Enhanced Pressure Dependence of Magnetic Exchange in A2+[V2]O4 Spinels Approaching the Itinerant Electron Limit
• Homopolar bond formation in ZnV${}_2$O${}_4$ close to a metal-insulator transition
• Pressure-induced insulator-to-metal transition in low-dimensional TiOCl
• Enhanced dimerization of TiOCl under pressure: spin-Peierls - to - Peierls transition
• Microscopic model for transitions from Mott to spin-Peierls insulator in TiOCl