Giant magnetocaloric effect, magnetization plateaux and jumps of the regular Ising polyhedra

TL;DR

This paper investigates the magnetization behavior and magnetocaloric effects of antiferromagnetic Ising spin clusters shaped as regular polyhedra, revealing giant effects and potential for low-temperature refrigeration due to geometric frustration.

Contribution

It provides exact analysis of magnetization plateaux, jumps, and the magnetocaloric effect in all regular Ising polyhedra, highlighting the role of geometric frustration in these phenomena.

Findings

Regular Ising polyhedra exhibit multiple magnetization plateaux.

Giant magnetocaloric effects occur near magnetization jumps.

Octahedron and dodecahedron clusters enable efficient low-temperature cooling.

Abstract

Magnetization process and adiabatic demagnetization of the antiferromagnetic Ising spin clusters with the shape of regular polyhedra (Platonic solids) are exactly examined within the framework of a simple graph-theoretical approach. While the Ising cube as the only unfrustrated (bipartite) spin cluster shows just one trivial plateau at zero magnetization, the other regular Ising polyhedra (tetrahedron, octahedron, icosahedron and dodecahedron) additionally display either one or two intermediate plateaux at fractional values of the saturation magnetization. The nature of highly degenerate ground states emergent at intermediate plateaux owing to a geometric frustration is clarified. It is evidenced that the regular Ising polyhedra exhibit a giant magnetocaloric effect in a vicinity of magnetization jumps, whereas the Ising octahedron and dodecahedron belong to the most prominent geometrically frustrated spin clusters that enable an efficient low-temperature refrigeration by the process of adiabatic demagnetization.