Heisenberg Dimer Single Molecule Magnets in a Strong Magnetic Field

TL;DR

This paper investigates the static and dynamic magnetic properties of single molecule Heisenberg dimers with spins 1/2 or 5/2 under strong magnetic fields, revealing quantum effects and calculating spectra relevant for experiments.

Contribution

It provides a detailed quantum mechanical analysis of single molecule magnets, including magnetization, specific heat, autocorrelation spectra, and neutron scattering at various temperatures and magnetic fields.

Findings

Quantum effects dominate at low temperatures and strong fields.

Calculated frequency spectra of autocorrelation functions.

Predicted neutron scattering structure factors for experimental validation.

Abstract

We calculate the static and dynamic properties of single crystal, single molecule magnets consisting of equal spin $S=1/2$ or 5/2 dimers. The spins in each dimer interact with each other via the Heisenberg exchange interaction and with the magnetic induction ${\bf B}$ via the Zeeman interaction, and interdimer interactions are negligible. For antiferromagnetic couplings, the static magnetization and specific heat exhibit interesting low temperature $T$ and strong ${\bf B}$ quantum effects. We calculate the frequency spectrum of the Fourier transform of the real part of the time autocorrelation function ${\cal C}_{11}(t)$ for arbitrary $T, {\bf B}$, and compare our results with those obtained for classical spins. We also calculate the inelastic neutron magnetic dynamical structure factor $S({\bf q},\omega)$ at arbitrary $T, {\bf B}$.