First-Principles study of an S = 1 quasi-1D quantum molecular magnetic material

TL;DR

This study employs density functional theory to analyze the structural, magnetic, and electronic properties of the quantum magnet DTN, successfully reproducing experimental observations and predicting effects of electric fields on its magnetic behavior.

Contribution

The paper introduces a computational approach combining GGA, van der Waals, and Hubbard U corrections to accurately model DTN's magnetic and electronic properties, including magneto-electric effects.

Findings

Reproduces magnetic anisotropy and exchange coupling in DTN

Provides electronic structure insights into magnetic interactions

Predicts electric field effects on magnetic properties

Abstract

We use density functional theory to study the structural, magnetic and electronic structure of the organo-metallic quantum magnet $\mathrm{NiCl_2-4SC(NH_2)_2}$ (DTN). Recent work has demonstrated the quasi-1D nature of the molecular crystal and its quantum phase transitions at low temperatures. This includes a magneto-electric coupling and, when doped with Br, the presence of an exotic Bose-glass state. We systematically show that, by using the generalized gradient approximation (GGA) with inclusion of a van der Waals term to account for weak inter-molecular forces and by introducing a Hubbard $U$ term to the total energy, our calculations reproduce the magnetic anisotropy, the inter-molecular exchange coupling strength and the magneto-electric effect in DTN, which were observed in previous experiments. Further analysis into the electronic structure gives insight into the underlying magnetic interactions, including what mechanisms may be causing the ME effect. Using this computationally efficient model, we predict what effect applying an electric field might have on the magnetic properties of this quantum magnet.