Triplon-spinon hybridization in Cu₃Mo₂O₉ observed using inelastic neutron scattering

We have measured the inelastic neutron scattering in Cu₃Mo ₂O₉ to study its dispersion curves of magnetic excitations. This system has the spin chains interacting with the isolated spin dimers. Therefore, the magnetic excitations of this system can be described as the hybridized modes between the magnetic excitations of the spin chain (spinon excitations) and those of the spin dimers (triplon ones). We estimate the amplitude of the exchange interaction in the spin chain (4.0 meV) and that of the spin dimers (5.8 meV). The hybridization parameter, i.e., the effective interaction between the spin chain and the spin dimer is estimated to be E _int sin (πk),where E_int = 1.6 meV. The modulation of the molecular field generated by the spin precession in the spinon excited state plays an essential role in the spinon-triplon hybridization.