Spin Solid versus Magnetic Charge Ordered State in Artificial Honeycomb Lattice of Connected Elements

TL;DR

This study investigates the low-temperature magnetic correlations in a novel artificial honeycomb lattice, providing experimental and simulation evidence for a spin solid state characterized by vortex loops, advancing understanding of magnetic states in nanostructures.

Contribution

It presents the first experimental confirmation of a spin solid state in connected artificial honeycomb lattices, supported by neutron scattering and micromagnetic simulations.

Findings

Development of a spin solid state below 7 K

Dominance of vortex loop configurations at low temperature

Confirmation of theoretical predictions in artificial nanostructures

Abstract

The nature of magnetic correlation at low temperature in two-dimensional artificial magnetic honeycomb lattice is a strongly debated issue. While theoretical researches suggest that the system will develop a novel zero entropy spin solid state as T --> 0 K, a confirmation to this effect in artificial honeycomb lattice of connected elements is lacking. We report on the investigation of magnetic correlation in newly designed artificial permalloy honeycomb lattice of ultra-small elements, with a typical length of ~ 12 nm, using neutron scattering measurements and temperature dependent micromagnetic simulations. Numerical modeling of the polarized neutron reflectometry data elucidates the temperature dependent evolution of spin correlation in this system. As temperature reduces to ~ 7 K, the system tends to develop novel spin solid state, manifested by the alternating distribution of magnetic vortex loops of opposite chiralities. Experimental results are complemented by temperature dependent micromagnetic simulations that confirm the dominance of spin solid state over local magnetic charge ordered state in the artificial honeycomb lattice with connected elements. Our results enable a direct investigation of novel spin solid correlation in the connected honeycomb geometry of two-dimensional artificial structure.