Giant Single-Molecule Magnets: A Mn84 Torus and its Supramolecular Nanotubes

TL;DR

This paper reports the synthesis of a giant Mn84 single-molecule magnet with a torus structure that exhibits both hysteresis and quantum tunneling, forming ordered supramolecular nanotubes, advancing nanoscale magnetic material development.

Contribution

We synthesized a large Mn84 SMM with a torus shape, demonstrating properties similar to smaller SMMs and forming ordered nanotube structures, bridging the size gap in molecular magnets.

Findings

Mn84 SMM has a 4 nm torus structure.

Displays magnetization hysteresis and quantum tunneling.

Crystallizes as ordered supramolecular nanotubes.

Abstract

The discovery a decade ago that individual molecules can function as magnetizable magnets provided a new, 'bottom-up' approach to nanoscale magnetic materials, and such molecules have since been called single-molecule magnets (SMMs). Each molecule functions as a nanoscale, single-domain magnetic particle that, below its blocking temperature (TB), exhibits the classical macroscale property of a magnet, namely magnetization hysteresis. In addition, they straddle the classical/quantum interface in also displaying quantum tunnelling of magnetization (QTM) and quantum phase interference, the properties of the atomic or microscale. SMMs have a number of potential applications, including very high density information storage, where each bit would be stored as the magnetization orientation of an individual molecule, and as quantum bits for quantum computing, taking advantage of the quantum superposition of states provided by the QTM. To facilitate development of techniques for addressing individual SMMs for such applications, and other reasons, it has been of interest to us to explore whether very large examples (by molecular standards) could be synthesized. In effect, can the molecular (or 'bottom-up') approach reach the size regime of the classical (or 'top-down') approach to nanoscale magnetic materials? Indeed, here we sure that a giant Mn84 SMM can be prepared with a torus structure of 4 nm dimensions, that it displays both magnetization hysteresis and QTM, and that it crystallizes as highly ordered, supramolecular nanotubes.