Dispersion relation of charge gap excitations in quasi-1D Mott insulators studied by resonant X-ray scattering

Momentum dependence of charge excitations across the effective Mott gap in several quasi-low-dimensional model cuprates with different effective dimensionalities is studied using high resolution inelastic X-ray scattering by working near Copper k  -edge resonance which allows us to extract the dispersion relations of the particle–hole pair excitations at the gap edge. Besides electron–electron correlation, momentum dependence of the gap-excitations is found to be strongly dependent on the effective dimensionality (or topology) of the 3dx2−y23dx2−y2 network.