Proposed low-energy model Hamiltonian for the spin-gapped system CuTe2O5

Using first-principles electronic structure calculations based on the Nth order muffin-tin orbital (NMTO)-downfolding technique, we derived the low-energy spin model for CuTe2O5. Our study reveals that this compound is a two-dimensional coupled spin-dimer system with the strongest Cu-Cu interaction mediated by two O-Te-O bridges. We checked the validity of our model by computing the magnetic susceptibility with quantum Monte Carlo technique and comparing it with available experimental data. We also present magnetization and specific-heat results which may be compared with future experimental investigations. Our derived model provides an alternative scenario to a recently proposed model for this compound [Phys. Rev. B 74, 174421 (2006)]. The situation needs to be settled in terms of further experimental investigations.