Emerging Chirality in Artificial Spin Ice

Abstract

Chiral Ice Water ice, even at the lowest temperatures, is not completely “frozen”—its lattice structure allows for multiple equivalent ground states and it thus retains finite entropy even at absolute zero. Equivalent structures are realized in frustrated magnets called spin ices, where spins interact ferromagnetically, and in the even more exotic artificial spin ices, which are fabricated arrays of nanoscale magnets. Branford et al. (p. 1597 ) studied the transport behavior of an artificial spin ice with a honeycomb geometry during upward and downward sweeps of an external magnetic field, which revealed a field-asymmetric peak when the magnetic field was applied parallel to the current and the voltage was measured transversely. Micromagnetic simulations suggest that the asymmetric response is a result of the loops of opposite handedness forming at the edges of the sample, resulting in an overall chirality of the transport response.