Temperature-dependent magnetism in artificial honeycomb lattice of connected elements

Artificial magnetic honeycomb lattices are expected to exhibit a broad and tunable range of novel magnetic phenomena that would be difficult to achieve in natural materials, such as long-range spin ice, entropy-driven magnetic charge-ordered states, and spin order due to the spin chirality. Eventually, the spin correlation is expected to develop into a unique spin-solid-state-density ground state, manifested by the distribution of the pairs of vortex states of opposite chirality. In this paper we report the creation of an artificial permalloy honeycomb lattice of ultrasmall connecting bonds, with a typical size of $\simeq 12$ nm. Detailed magnetic and neutron-scattering measurements on the newly fabricated honeycomb lattice demonstrate the evolution of magnetic correlation as a function of temperature. Finally, at low enough temperature, neutron-scattering measurements and micromagnetic simulation suggest the development of a loop state of vortex configuration in this system.