L. A. S. Mól, A. R. Pereira, W. A. Moura-Melo
In this work we propose and study a realization of an artificial spin
ice-like system, not based on any real material, in a triangular geometry. At
each vertex of the lattice, the "ice-like rule" dictates that three spins must
point inward while the other three must point outward. We have studied the
system's ground-state and the lowest energy excitations as well as the
thermodynamic properties of the system. Our results show that, despite
fundamental differences in the vertices topologies as compared to the
artificial square spin ice, in the triangular array the lowest energy
excitations also behave as a kind of Nambu monopoles (two opposite monopoles
connected by an energetic string). Indeed, our results suggest that the
monopoles charge value may have a universal value while the string tension
could be tuned by changing the system's geometry, probably allowing the design
of systems with different string tensions. Our Monte Carlo results suggest a
phase transition in the Ising universality class where the mean distance
between monopoles and anti-monopoles increases considerably at the critical
temperature. The differences on the vertices topologies seem to facilitate the
experimental achievement of the system's ground-state, thereby allowing a more
detailed experimental study of the system's properties.
View original:
http://arxiv.org/abs/1112.0515
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