Magnetization curves and low-temperature thermodynamics of two spin-1/2 Heisenberg edge-shared tetrahedra

TL;DR

This paper provides an exact analysis of the energy spectrum, magnetization, and susceptibility of a spin-1/2 Heisenberg model on two edge-shared tetrahedra, revealing diverse ground states and magnetization plateaux influenced by coupling constants.

Contribution

It offers the first exact calculation of thermodynamic properties for this specific spin model, connecting theoretical predictions with experimental data on mineral crystal fedotovite.

Findings

Ground state varies between singlet and triplet depending on coupling ratios.

Multiple intermediate magnetization plateaux observed at fractional saturation levels.

Theoretical susceptibility matches temperature-dependent experimental data.

Abstract

A full energy spectrum, magnetization and susceptibility of a spin-1/2 Heisenberg model on two edge-shared tetrahedra are exactly calculated by assuming two different coupling constants. It is shown that a ground state in zero field is either a singlet or a triplet state depending on a relative strength of both coupling constants. Low-temperature magnetization curves may exhibit three different sequences of intermediate plateaux at the following fractional values of the saturation magnetization: 1/3-2/3-1, 0-1/3-2/3-1 or 0-2/3-1. The inverse susceptibility displays a marked temperature dependence significantly influenced by a character of the zero-field ground state. The obtained theoretical results are confronted with recent high-field magnetization data of the mineral crystal fedotovite K2Cu3(SO4)3.