Giant Keplerate molecule Fe30 - the first octopole magnet

TL;DR

This paper applies multipole expansion to the Fe30 molecule, revealing it as the most symmetrical magnetic body with a dominant octopole moment, and discusses its magnetization behavior and experimental measurement prospects.

Contribution

It introduces the first detailed analysis of Fe30's octopole magnetic moment, highlighting its unique symmetry and proposing experimental measurement methods.

Findings

Fe30 has zero dipole, toroid, and quadrupole moments.

Magnetization shows jumps in octopole components during saturation.

Proposes an experiment to measure octopole moments.

Abstract

The multipole expansion technique is applied to one of the largest magnetic molecules, Fe30. The molecule's dipole, toroid and quadrupole magnetic moments are equal to zero (in the absence of magnetic field) so the multipole expansion starts from the octopole moment. Probably the Fe30 molecule is the most symmetrical magnetic body synthesized so far. The magnetization process is considered theoretically in different geometries. Some components of the octopole moment experience a jump while the magnetization rises linearly up to its saturation value. An elementary octopole moment consisting of four magnetic dipoles is proposed as a hint for designing of an experiment for measurement of octopole magnetic moment components.