Influence of Lattice Parameter Scaling on Local Electronic and Magnetic Properties in La₂CuO₄

Abstract

A large amount of static and dynamic NMR experiments have been carried out to determine the spin properties in high temperature superconductors cuprates (HTSC). In the majority of cuprates the magnetic shift at the planar copper nucleus is independent of the temperature when the field is applied perpendicular to the CuO₂ planes and does not exhibit the expected reduction of the spin susceptibility in the superconducting state. This has been explained by a coincidental cancellation of on-site and transferred hyperfine fields at the copper nucleus, which would lead to a vanishing spin shift. To examine this explanation we determine the hyperfine fields by ab initio cluster calculations for La₂CuO₄ within the framework of spin-polarized density functional theory. In particular we investigate the sensitivity of the hyperfine fields on the lattice constants.