Nuclear Quadrupole Resonance Frequency in Multi-Layered Cuprates

TL;DR

This study calculates the 63Cu NQR frequency in multi-layered cuprates using a cluster model, revealing its effectiveness in estimating charge imbalance and predicting enhancements in multilayered structures.

Contribution

It introduces a theoretical calculation of NQR frequency in multi-layered cuprates and predicts charge imbalance effects in complex structures.

Findings

NQR frequency can estimate charge imbalance in cuprates.

Charge transfer energy influences NQR frequency splitting.

Predicted large NQR splitting in multilayered cuprates with more than three layers.

Abstract

The 63Cu nuclear quadrupole resonance (NQR) frequency, nu_q, in the multi-layered cuprates is calculated in the cluster model by the exact diagonalization method. The charge imbalance between the outer CuO_2 plane (OP) with apical oxygen (OA) and the inner plane (IP) without OA in three-layered Tl2223 is estimated by comparing our results with the experimental nu_q. In Tl-based cuprates with more than three layers, we predict a large enhancement of the splitting of nu_q between OP and IP by taking into account the reduction of bond length between Cu and OA and a resulting enhancement of the charge transfer energy. Our results show that the NQR frequency is a useful quantity to estimate the charge imbalance in the multi-layered cuprates.