Spin-Peierls instabilities of antiferromagnetic rings in a magnetic field

Abstract

Motivated by the intriguing properties of magnetic molecular wheels at field induced level crossings, we investigate the spin-Peierls instability of antiferromagnetic rings in a field by exact diagonalizations of a microscopic spin model coupled to the lattice via a distortion dependent Dzyaloshinskii-Moriya interaction. We show that, beyond the unconditional instability at level crossings for infinitesimal magnetoelastic coupling, the model is characterized by a stronger tendency to distort at higher level crossings, and by a dramatic angular dependence with very sharp torque anomalies when the field is almost in the plane of the ring. These predictions are shown to compare remarkably well with available torque and Nuclear Magnetic Resonance data on CsFe8.

Revised text + figs

References in corpus (3)

• Uniform and staggered magnetizations induced by Dzyaloshinskii-Moriya interactions in isolated and coupled spin 1/2 dimers in a magnetic field
• Field-induced level crossings in spin clusters: Thermodynamics and magneto-elastic instability
• Huge Transverse Magnetization in the Field-Induced Phase of the Antiferromagnetic Molecular Wheel CsFe8

Cited by in corpus (3)

• Quantized antiferromagnetic spin waves in the molecular Heisenberg ring CsFe${}_8$
• Spin-phonon interaction induces tunnel splitting in single-molecule magnets
• Torque anomalies at magnetization plateaux in quantum magnets with Dzyaloshinskii-Moriya interactions