Time-domain study of spin-wave dynamics in two-dimensional arrays of bi-component magnetic structures

Abstract

Spin-waves in single Ni80Fe20 (Py) and Co bi-component units embedded in two-dimensional arrays thereof are investigated by all-optical time-resolved magneto-optical Kerr effect microscope. Two bands of modes observed for the bias field applied along the long-axis of the bi-component unit convert into four distinct bands, and the mode frequencies change significantly as the field is rotated to the short-axis. Micromagnetic simulations reproduce the experimental results, and comparison with single Py and Co elements and single bi-component unit reveals significant variations of mode frequencies and mode profiles, indicating opportunities for magnonic band engineering in this type of bi-component arrays. The authors gratefully acknowledge the financial supports from the Department of Science and Technology, Government of India under Grant Nos. SR/NM/NS-53/2010 and SR/WOS-A/PS-27/2010, Department of Information Technology, Government of India under Grant No. 1(7)/2010/M&C, the Ministry of Education, Singapore, and the SMF-NUS New Horizon Awards. S.S. acknowledges UGC, Government of India for senior research fellowship.