Classical dipoles on the kagome lattice

Abstract

Motivated by recent developments in magnetic materials, frustrated nanoarrays and cold atomic systems, we investigate the behaviour of dipolar spins on the frustrated two-dimensional kagome lattice. By combining the Luttinger-Tisza approach, numerical energy minimization, spin-wave analysis and parallel tempering Monte-Carlo, we study long-range ordering and finite-temperature phase transitions for a Hamiltonian containing both dipolar and nearest-neighbor interactions. For both weak and moderate dipolar interactions, the system enters a three-sublattice long-range ordered state, with each triangle having vanishing dipole and quadrupole moments; while for dominating dipolar interactions we uncover ferrimagnetic three-sublattice order. These are also the ground states for XY spins. We discuss excitations of, as well as phase transitions into, these states. We find behaviour consistent with Ising criticality for the 120-degree state, while the ferrimagnetic state appears to be associated with drifting exponents. The celebrated flat band of zero-energy excitations of the kagome nearest-neighbour Heisenberg model is lifted to finite energies but acquires only minimal dispersion as dipolar interactions are added.

9 pages, 8 figures

References in corpus (6)

• Artificial "spin ice" in a geometrically frustrated lattice of nanoscale ferromagnetic islands
• Artificial square ice and related dipolar nanoarrays
• Anomalous Behavior of Spin Systems with Dipolar Interactions
• Dipolar order by disorder in the classical Heisenberg antiferromagnet on the kagome lattice
• Evidence for gapped spin-wave excitations in the frustrated Gd2Sn2O7 pyrochlore antiferromagnet from low-temperature specific heat measurements
• Infinite Geometric Frustration in a Cubic Dipole Cluster

Cited by in corpus (6)

• Persistence of the flat band in a kagome magnet with dipolar interactions
• Continuous ground-state degeneracy of classical dipoles on regular lattices
• Zero-energy excitation in the classical kagome antiferromagnet NaBa${}_2$Mn${}_3$F${}_{11}$
• Effects of exchange distortions in the magnetic Kagome lattice
• Molecular dipoles in designer honeycomb lattices
• Magnetic order in the chemically-substituted frustrated antiferromagnet CsCrF${}_4$