Crystal-field spectrum of R_1-yCa_yBa₂Cu₃O_x high-T_c superconductors in the overdoped regime

Recent inelastic neutron scattering measurements revealed the crystal-field spectra of the overdoped R_1-yCa_yBa₂Cu₃O_≃7 (R=Ho, Er;0 < y < 0.2) high-T_c superconductors to consist of two spectral components associated with the optimally doped and the overdoped domains, respectively. Increase of the Ca concentration does not affect the local charge density of domains, but changes the spectral weight of the components. In the sense of this 'two-phase' picture, which was established earlier for the underdoped region, there is a smooth crossover between the underdoped and overdoped parts of the phase diagram. However, these two regions are characterized by a qualitatively different type of in-plane charge distribution.