Magneto-elastic instability in Molecular Antiferromagnetic Rings

TL;DR

This paper investigates how magneto-elastic instabilities in antiferromagnetic rings depend on spin and size, highlighting Cu8 as a promising candidate for observing lattice dimerization and analyzing thermal effects.

Contribution

It provides a detailed analysis of lattice stability in antiferromagnetic rings, emphasizing the influence of spin value and identifying Cu8 as a key material for experimental observation.

Findings

Magneto-elastic transition varies with spin, showing qualitative differences for spin-1/2.

Cu8 is identified as the best candidate for observing lattice dimerization.

Thermal fluctuations induce a crossover temperature affecting lattice stability.

Abstract

Lattice stability in a model of antiferromagnetic ring coupled to adiabatic phonons is investigated for different values of the spin and numbers of magnetic sites. The magneto-elastic transition is shown to be heavily affected by the spin value, displaying a qualitative difference in the nature of the instability for spin one-half. Among the different synthesized materials, Cu$_8$ seems to be the best candidate to observe lattice dimerization in these systems. Our analysis excludes stable lattice distortions in higher spin rings. The effects of thermal fluctuations are studied in the Cu$_8$ model, where a characteristic crossover temperature is estimated.