Long-range ferromagnetic dipolar ordering of high-spin molecular clusters

TL;DR

This paper demonstrates the first instance of long-range ferromagnetic order driven solely by dipolar interactions in a high-spin molecular cluster, revealing new insights into magnetic ordering at the molecular level.

Contribution

It reports the discovery of dipolar-driven magnetic order in a molecular magnet with minimal anisotropy, a novel phenomenon in the field.

Findings

Long-range order occurs at Tc = 0.16 K

Fast spin-lattice relaxation persists down to lowest temperatures

High magnetic fields significantly reduce relaxation rates

Abstract

We report the first example of a transition to long-range magnetic order in a purely dipolarly interacting molecular magnet. For the magnetic cluster compound Mn6O4Br4(Et2dbm)6, the anisotropy experienced by the total spin S=12 of each cluster is so small that spin-lattice relaxation remains fast down to the lowest temperatures, thus enabling dipolar order to occur within experimental times at Tc = 0.16 K. In high magnetic fields, the relaxation rate becomes drastically reduced and the interplay between nuclear- and electron-spin lattice relaxation is revealed.