Doping-induced spin-manipulation in complex trimer system Ca3Cu3(PO4)4: A density functional investigation

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 Ca3Cu3(PO4)4 with doublet ground state. The present study is a first-principles based investigation of the effects of such doping on the spinexchange 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.

Full propagation-vector star antiferromagnetic order in quantum spin trimer system Ca3CuNi2(PO4)4

“…We find that such good correspondence between experiment and theory is a strong complementary argument in favour of the full star model. The numerical density functional investigations [21] with both inter-and intra-trimer interactions included, but without single ion anisotropy are also in good agreement with the experiment. The calculations give similar magnetic moment value 1.8 µ B for Ni and slightly larger for Cu 0.8 µ B , and somewhat smaller Cu-Ni intratrimer interaction [21] in comparison with [4,5].…”