First principles study of local electronic and magnetic properties in pure and electron-doped Nd$_2$CuO$_4$

TL;DR

This study uses ab-initio calculations to analyze the local electronic and magnetic properties of Nd2CuO4, focusing on electron doping effects and comparing results with La2CuO4, providing insights into charge distribution and NMR-related properties.

Contribution

It presents a detailed ab-initio analysis of electron-doped Nd2CuO4's local electronic and magnetic properties, including electric field gradients and NMR parameters, with comparisons to La2CuO4.

Findings

Reduction in EFG at Cu nucleus with electron doping

Decrease in 3d3z^2-r^2 orbital occupancy due to doping

Good agreement between calculated and experimental EFG values

Abstract

The local electronic structure of Nd2CuO4 is determined from ab-initio cluster calculations in the framework of density functional theory. Spin-polarized calculations with different multiplicities enable a detailed study of the charge and spin density distributions, using clusters that comprise up to 13 copper atoms in the CuO2plane. Electron doping is simulated by two different approaches and the resulting changes in the local charge distribution are studied in detail and compared to the corresponding changes in hole doped La2CuO4. The electric field gradient (EFG) at the copper nucleus is investigated in detail and good agreement is found with experimental values. In particular the drastic reduction of the main component of the EFG in the electron-doped material with respect to LaCuO4 is explained by a reduction of the occupancy of the 3d3z^2-r^2 atomic orbital. Furthermore, the chemical shieldings at the copper nucleus are determined and are compared to results obtained from NMR measurements. The magnetic hyperfine coupling constants are determined from the spin density distribution.