Incommensurate spin correlation driven by frustration inBiCu2PO6

The magnetic properties of ${\text{BiCu}}_{2}{\text{PO}}_{6}$ have been analyzed by means of magnetic-susceptibility and inelastic neutron-scattering measurements on powder samples by evaluating the spin-exchange interactions on the basis of density-functional calculations and by simulating the inelastic neutron scattering in terms of spin-exchange parameters. ${\text{BiCu}}_{2}{\text{PO}}_{6}$ exhibits magnetic properties described by the two-leg spin ladder with strong spin frustration along each leg chain and has a gapped quantum singlet ground state with excited magnetic states, showing an incommensurate dispersion arising from frustration.