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 (S) over right arrow (s). The discs couple to each other by their dipolar stray fields, resulting in an interaction of the form J(ij)(s) over right arrow (i) (.) (S) over right arrow (j), 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.