Photo-induced and doping effects on the non-linear excitation in [PtX2(en)][PtX4(en)](X=Cl, Br, I)

We have investigated the photo-induced and doping effects on the non-linear excitations (i.e. solitons and polarons) for the neutral MX chain system, [PtX2(en)][PtX4(en)](X=Cl, Br, I). From the analysis of the hyperfine structure of ESR signal in X=Cl salt, the photo-induced non-linear excitation is attributed to the neutral soliton. The iodine-doped X=Cl salt reveals a strong and broad ESR signal, whose intensity and g-value as a function of temperature suggest the existence of the dense non-linear excitations and the strong magnetic interaction between them.