DOPANT-BOUND SPINONS IN CU1-XZNXGEO3

Polarized inelastic light scattering experiments on Cu1-xZnxGeO3 (0 le ss than or equal to x less than or equal to 0.045) single crystals sho w for x not equal 0 a new distinct mode at nearly half the energy of t he singlet response below the spin-Peierls transition. The temperature , magnetic field, polarization, and doping dependences of this mode ar e similar to those of the singlet bound state. The data are interprete d in terms of a spinon-assisted light scattering process. Position and form of the peak provide strong evidence for the presence of dopant-b ound spinons in Cu1-xZnxGeO3.