Using Structural Phase Transitions to Enhance the Coercivity of Ferromagnetic Films
Ryan F Need, Josh Lauzier, Logan Sutton, Brian J Kirby, Jose de la Venta
Storing information in magnetic recording technologies requires careful optimization of the recording media's magnetic properties. For example, heat-assisted magnetic recording (HAMR) relies on a pre-recording heating step that momentarily lowers the coercivity of the ferromagnetic recording media, and thereby decreases the energy required for each writing operation. However, reducing the coercivity of common storage media can require local temperature increases of several hundred Kelvin, which turn can cause lateral heat spreading and limit recording rates. Here, we describe a mechanism for creating dramatic changes in the coercivity of ferromagnetic films over small temperature ranges, by coupling them to an adjacent layer that undergoes a structural phase transition with large volume change. The method is demonstrated in Ni/FeRh bilayers where the Ni layer was deposited by 300 K and 523 K, above and below the FeRh metamagnetic transition at ~300 K. When the Ni layer is grown at high temperatures and then cooled, the ~1% FeRh lattice contraction strains the overlying Ni and promotes domain wall pinning that increases the coercivity by 500% over a 50 K temperature window. This ability to thermally tun the coercivity of ferromagnetic materials may open up new materials to HAMR and new avenues to magnetic information storage.
, Lauzier, J.
, Sutton, L.
, , B.
and de, J.
Using Structural Phase Transitions to Enhance the Coercivity of Ferromagnetic Films, APL Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928476
(Accessed December 9, 2023)