Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

We report on the crystal structure and magnetic behavior of the spin-1/2 compound AgVOAsO₄. Magnetic susceptibility, high-field magnetization, and electron spin resonance measurements identify AgVOAsO₄ as a gapped quantum magnet with a spin gap Delta similar or equal to 13 K and a saturation field mu₀H_s similar or equal to 48.5 T. Extensive band structure calculations establish the microscopic magnetic model of spin chains with alternating exchange couplings J similar or equal to 40 K and J' similar or equal to 26 K. However, the precise evaluation of the spin gap emphasizes the role of interchain couplings which are frustrated due to the peculiar crystal structure of the compound. The unusual spin model and the low energy scale of the exchange couplings make AgVOAsO₄ a promising candidate for an experimental investigation of Bose-Einstein condensation in high magnetic fields.