Spin-interactions in Mineral Libethenite Series: Evolution of Low-dimensional Magnetism

TL;DR

This study investigates the evolution of magnetic interactions in the mineral series A2PO4OH (A=Co, Cu), revealing a transition from 3D antiferromagnetism to low-dimensional frustrated magnetism through detailed electronic structure analysis and modeling.

Contribution

It provides a comprehensive analysis of spin-exchange interactions and magnetic evolution in the Libethenite series using advanced density-functional methods and minimal spin-Hamiltonian models.

Findings

Transition from 3D antiferromagnet to low-dimensional frustrated magnetism

Identification of magnetic exchange mechanisms via electronic structure calculations

Evaluation of spin-gap and effects of size-confinement on magnetic properties

Abstract

Interesting magnetic properties and spin-exchange interactions along various possible pathways in half-integral spin quantum magnetic tetramer system: A$_{2}$PO$_{4}$OH (A = Co, Cu) are investigated. Interplay of structural distortion and the magnetic properties with the evolution of localized band structure explain the gradual transition from a three-dimensional antiferromagnet to a low-dimensional frustrated magnetic system along the series. Detailed study of exchange mechanism in this system explores various possibilities of complex magnetic interaction. Electronic structure of this series, studied with the help of different appropriate density-functional approaches like N-th order Muffin-Tin orbital(NMTO) and Planewave Pseudopotential calculations incorporating onsite Coulomb repulsion(U), identifies the underlying magnetic exchange mechanism of this series. Thereafter a generalized minimal model spin-Hamiltonian is constructed for the low-dimensional system. Solution of this model Hamiltonian within first order perturbation theory results into the evaluation of spin-gap in the spin-tetramer system. In addition, the effects of size-confinement and volume reduction on the relevant exchange integrals and spin-gap of the low-dimensional system are also discussed.