Carrier localization, Anderson transitions and stripe formation in hole-doped cuprates

Abstract

Three distinctly different scenarios are proposed for the carrier localization in three- dimentional (3D) lightly doped cuprates in which the self-trapping and pairing of hole carriers (i) near the small-radius dopants and (ii) in a defect-free deformable lattice lead to the formation of the extrinsic and intrinsic (bi)polaronic states in the charge-transfer gap of the cuprates, and (iii) the self-trapping of hole carriers away from the large-radius dopants results in the formation of the in-gap hydrogenic impurity states. We have shown that the extrinsic and intrinsic 3D large bipolarons exist in La-based lightly doped cuprates at η = ɛ∞/ɛ0 < 0:127 and η < 0:138, respectively, where ɛ∞/ɛ0 is the optic (static) dielectric constant. We use the uncertainty relation to obtain the specificc conditions for the Anderson and new MITs in cuprates. The applicability limits of these MITs in La-based cuprates are clarified. Our results are in good agreement with the existing experiments on La-based cuprates.