On the realization of artificial XY spin chains

Spin chains are the most elementary entities in the study of magnetic ordering behaviour. In this letter, we describe a route toward the realization of artificial XY spin chains. Using thin-film deposition and e-beam lithography, 300 and 550 nm diameter pillars consisting of alternating discs of permalloy and Al₂O₃ have been made. Shape anisotropy forces the magnetization in plane, creating a chain of two-dimensional magnetic moments . The discs couple to each other by their dipolar stray fields, resulting in an interaction of the form , with J_ij the coupling between discs i and j. This form closely resembles a chain of xy spins, coupled by effective interactions J_ij. We present a magnetic characterization of the pillars, and compare the results with model calculations. Also, spin dynamics and ordering phenomena are addressed.