Magnetic order in the two-dimensional metal-organic framework manganese pyrazinecarboxylate with Mn-Mn dimers

TL;DR

This study investigates the magnetic properties of a 2D metal-organic framework with Mn-Mn dimers, revealing a two-stage magnetic transition and a specific antiferromagnetic structure through various experimental techniques.

Contribution

It provides the first detailed characterization of magnetic order and phase transitions in Mn-pyrazine, a quasi-2D MOF with Mn-Mn dimers, using susceptibility, heat capacity, and neutron scattering.

Findings

Two-stage magnetic transition at 5 K and 3.3 K

Magnetic field can induce transitions at 2 T

Determined magnetic structure with antiferromagnetic Mn-Mn dimers

Abstract

The magnetic properties of [Mn(pyrazinecarboxylate)2]n (Mn-pyrazine), empirical formula C10H6MnN4O4, are investigated through susceptibility, heat capacity and neutron scattering measurements. The structure of Mn-pyrazine consists of Mn-Mn dimers linked on a distorted 2D hexagonal structure. The weak out of plane interactions create a quasi-2D magnetic material within the larger three dimensional metal organic framework (MOF) structure. We show that this material undergoes a two stage magnetic transition, related to the low dimensionality of the Mn lattice. First at 5 K, which is assigned to the initial development of short range order in the 2D layers. This is followed by long range order at 3.3 K. Applied field measurements reveal the potential to induce magnetic transitions in moderately small fields of 2 T. Neutron powder diffraction enabled the determination of a unique magnetic space group P21'/c (#14.77) at 1.5 K. This magnetic structure consists of antiferromagnetically coupled Mn-Mn dimers with spins principally along the out of plane a-axis.