Thermodynamics of emergent magnetic charge screening in artificial spin ice

Abstract

Electric charge screening is a fundamental principle governing the behaviour in a variety of systems in nature. Through reconfiguration of the local environment, the Coulomb attraction between electric charges is decreased, leading, for example, to the creation of polaron states in solids or hydration shells around proteins in water. Here, we directly visualize the real-time creation and decay of screened magnetic charge configurations in a two-dimensional artificial spin ice system, the dipolar dice lattice. By comparing the temperature dependent occurrence of screened and unscreened emergent magnetic charge defects, we determine that screened magnetic charges are indeed a result of local energy reduction and appear as a transient minimum energy state before the system relaxes towards the predicted ground state. These results highlight the important role of emergent magnetic charges in artificial spin ice, giving rise to screened charge excitations and the emergence of exotic low-temperature configurations.

Thermally induced magnetic relaxation in square artificial spin ice

“…This facilitates the study of dynamics in many-body systems on adjustable length, energy and time scales, enabling the design of new devices with tailored electromagnetic properties in the relevant frequency regimes2627. The new emergent dynamics of mesoscale objects, such as the patterned nanomagnets comprising the artificial spin ice arrays and the related magnetic charge defects due to thermal fluctuations, further highlight the promise these systems offer in the design of reconfigurable magnonic devices2225.…”

“…Concerning the collective dynamics of mesoscale magnetic systems, much remains to be explored, especially with respect to the temporal dynamics1622 and phase transitions23. Artificial spin ice and more general artificial ferroic systems are micro-magnetic variants of interacting many-body systems15.…”

“…Artificial spin ice and more general artificial ferroic systems are micro-magnetic variants of interacting many-body systems15. These have developed over the past years from a testbed for the study of ground-state ordering and low-energy behavior, to a playground for the exploration of collective excitations and dynamics16172224. Artificial ferroic systems with tunable dynamical properties can be designed by considering different materials and geometries rather than being limited just by microscopic material properties25.…”

Magnetotransport in Artificial Kagome Spin Ice

“…Magnetic charge degrees of freedom play a prominent role in the physics of spin ice materials. In particular, artificial spin ices containing vertices of odd coordination numbers exhibit novel phenomena that can be attributed to the existence of the uncompensated background magnetic charges [8][9][10][11][12][13][14]. A remarkable example is the kagome spin ice in which a spontaneous ordering of magnetic charges precedes the long-range spin order [8,9].…”

Monte Carlo simulation on a new artificial spin ice lattice consisting of hexagons and three-moment vertices

“…At low temperature there is zero charge in most z6 vertices the z3 vertices show a clear tendency towards obeying the ice rule in the dice lattice. 26 Both the shakti lattice and the dice lattice focused on the vertices and introduce mixed coordination. The hexagon is a typical feature in the kagome lattice, while it's not an independent unit since it shares sides with adjacent hexagons.…”