Magneto-elastic instability in Molecular Antiferromagnetic Rings

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.

4 pages, 4 figures; to appear in PRL

References in corpus (6)

• Geometric Aspects of Quantum Spin States
• Macroscopic Quantum Coherence in Molecular Magnets
• The Stability of the Peierls Instability for Ring-Shaped Molecules
• Numerical Study of the Incommensurate Phase in Spin-Peierls Systems
• Tetramerisation of a frustrated spin-1/2 chain
• Spin-Peierls transition of the first order in S=1 antiferromagnetic Heisenberg chains

Cited by in corpus (6)

• Field-induced magnetoelastic instabilities in antiferromagnetic molecular wheels
• Field-induced level crossings in spin clusters: Thermodynamics and magneto-elastic instability
• Spin-Peierls instabilities of antiferromagnetic rings in a magnetic field
• Spin dynamics in molecular ring nanomagnets: Significant effect of acoustic phonons and magnetic anisotropies
• Lattice effects on the spin dynamics in antiferromagnetic molecular rings
• Dynamic spin Jahn-Teller effect in small magnetic clusters