Exchange energies of Kapellasite from high-temperature series analysis of the kagome lattice J1-J2-Jd-Heisenberg model

TL;DR

This paper develops a method to model magnetic properties of insulators using high-temperature series expansions, successfully applied to kapellasite, revealing specific exchange interactions and confirming its phase in the Heisenberg model.

Contribution

It introduces a fitting approach combining susceptibility and specific heat data to determine exchange energies in kagome lattice magnets.

Findings

Reproduces experimental data with specific exchange parameters

Confirms kapellasite's placement in the cuboc2 phase

Establishes constraints on exchange energy values

Abstract

We present a method to build magnetic models for insulators based on high-temperature expansions by fitting both the magnetic susceptibility and the low temperature specific heat data. It is applied to the frustrated magnet kapellasite (Cu3Zn(OH)6Cl2) with the J1-J2-Jd-Heisenberg model on the kagome lattice. Experimental data are reproduced with a set of "competing" exchange energies closed to J1 = -12K, J2= -4K and Jd=15.6K, where Jd is the third neighbor exchange energy across the hexagon. Strong constrains between these exchange energies are established. These values confirm the results of B. F{\aa}k et al. (Phys. Rev. Lett., 109, 037208 (2012)) regarding the location of kapellasite in the {\it cuboc2} phase of the Heisenberg model. The quality and limits of this modeling are discussed.