Characterising the Holmium contribution to excitations in Holmium Iron Garnet

Rare-earth Iron garnets (R3Fe5O12) have been in the focus of active research for the last five decades due to properties such as magnetostriction, magneto-optical effects, as well as applications in spintronics and magnonics. With the notable exception of Yttrium Iron Garnet, very little work exists on momentum resolved studies of the magnetic excitations in these compounds. It is of both fundamental and practical interest to explore the effect of a magnetic A-site in these systems, particularly with regard to understanding how this is likely to affect functional properties such as the spin Seebeck effect and the magnon thermal conductivity. The core aim of this study supplement our recent high energy measurements by studying the low energy modes of Holmium Iron Garnet (which belong to Holmium A-site), and which will complete the picture on the exchange interactions for this material.