Dipolar needles in the microcanonical ensemble: evidence of spontaneous magnetization and ergodicity breaking

Abstract

We have studied needle shaped three-dimensional classical spin systems with purely dipolar interactions in the microcanonical ensemble, using both numerical simulations and analytical approximations. We have observed spontaneous magnetization for different finite cubic lattices. The transition from the paramagnetic to the ferromagnetic phase is shown to be first-order. For two lattice types we have observed magnetization flips in the phase transition region. In some cases, gaps in the accessible values of magnetization appear, a signature of the ergodicity breaking found for systems with long-range interactions. We analytically explain these effects by performing a nontrivial mapping of the model Hamiltonian onto a one-dimensional Ising model with competing antiferromagnetic nearest-neighbor and ferromagnetic mean-field interactions. These results hint at performing experiments on isolated dipolar needles in order to verify some of the exotic properties of systems with long-range interactions in the microcanonical ensemble.

References in corpus (6)

• Statistical mechanics and dynamics of solvable models with long-range interactions
• Phase space gaps and ergodicity breaking in systems with long range interactions
• Long-Range Effects in Layered Spin Structures
• Long-range gravitational-like interaction in a neutral atomic cold gas
• The ferromagnetic transition and domain structure in LiHoF4
• Experimental perspectives for systems based on long-range interactions

Cited by in corpus (8)

• Spreading of Perturbations in Long-Range Interacting Classical Lattice Models
• Traveling Solitons in Long-Range Oscillator Chains
• Topological Kinetic Crossover in a Nanomagnet Array
• The effect of long-range interactions on the dynamics and statistics of 1D Hamiltonian lattices with on-site potential
• Direction of cascades in a magnetofluid model with electron skin depth and ion sound Larmor radius scales
• Dynamics and thermodynamics of a pair of interacting magnetic dipoles
• Effective negative specific heat by destabilization of metastable states in dipolar systems
• Spin waves in rings of classical magnetic dipoles