Doping-induced spin-manipulation in complex trimer system Ca$_{3}$Cu$_{3}$(PO$_{4}$)$_{4}$: A First Principles Study

TL;DR

This study uses first-principles calculations to explore how magnetic and non-magnetic doping affects the spin states and electronic structure of a Cu-based trimer compound, revealing Mg doping more effectively induces a singlet ground state.

Contribution

It provides a detailed first-principles analysis of doping effects on spin exchange and electronic structure, highlighting the efficiency of Mg doping in achieving a spin-gap system.

Findings

Mg doping is more effective than Ni in inducing a singlet ground state.

Doping leads to a dimerized state with lowest energy.

Calculated spin exchange values match experimental results.

Abstract

Spin-manipulated doping with magnetic (Ni) and non-magnetic (Mg) dopants constitutes the experimental attempts to obtain a singlet ground state system from the linear chain Heisenberg antiferromagnetic Cu-based $d^{9}$ spin-1/2 trimer compound Ca$_{3}$Cu$_{3}$(PO$_{4}$)$_{4}$ with doublet ground state. The present study is a first-principles based investigation of the effects of such doping on the spin-exchange mechanism and electronic structure of the parent compound. Site-selective doping with zero-spin dopants like Mg is proved to be more efficient than an integral spin dopant Ni in obtaining a spin-gap system with singlet ground state, as also observed in the experimental studies. Doping induced dimerized state is found to be the lowest in ground-state energy. Calculated spin exchange values along various possible paths resemble nicely with earlier experimental results.