Influence of dipolar interaction on the spin-wave mode propagation in artificial spin ice*

Artificial Spin Ice¹ systems are strongly dipolar coupled elongated magnetic nanoislands which are used as model systems to study the spin ice behavior observed in pyrochlore oxides as Dy₂Ti₂O₇. Lately, there is an emphasis on the understanding of spin wave (sw) dynamics in such systems as they offer an intriguing possibility to tune sw behavior and manipulate sw band gaps. Hence, these systems are also considered as key candidates for reconfigurable magnonics². We have thus performed a detailed analysis of the role of dipolar interaction on the sw dynamics and propagation in square artificial spin ice (S-ASI). We report that spin wave generation at particular frequencies can be realized even in the region of zero excitation due to strong dipolar coupling in such systems. This suggests the possibility of directional propagation of sw using reconfigurable ASI which can be employed in low power consumption based information processing devices. Additionally, our study suggests that S-ASI can be considered as a combination of four square rings of similar nanoislands of permalloy as a single square ring is adequate to understand sw dynamics in S-ASI.
¹R. Wang et al., Nature 439, 303 (2006).
²S. Mamica et al., Adv. Cond. Mat. Phys. 2012 (2012).