Lattice distortion near T* in lightly doped La2CuO4+δ

Establish whether a lattice distortion occurs near T* ≅ 280 K in lightly doped La2CuO4+δ with p ≅ 0.03 and determine whether it changes the occupation of doped holes among apical and in-plane electronic orbitals.

Background

The paper proposes that the simultaneous anomalies in magnetism and electrical conduction below T* may result from a lattice distortion that increases the contribution of apical O 2p_z and Cu 3d3z2−r2 orbitals to low-energy states, while reducing hole occupation in the in-plane O 2p_x(y) and Cu 3dx2−y2 orbitals.

Such a redistribution could weaken the transport anisotropy and reduce the disturbance of two-dimensional antiferromagnetic correlations by mobile holes. Although related lattice anomalies have been reported in La2CuO4+δ, the paper does not establish that the proposed distortion occurs at T* in the homogeneous p ≅ 0.03 antiferromagnetic–superconducting state.