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MATERIALS ENGINEERING

SEMINAR

“Towards Plasmonic-assisted Magnetization Switching”

By

Alan Hwader Chu

Purdue MSE Preliminary Exam

Advisor: Professor Ernesto E. Marinero

ABSTRACT

All-optical magnetization switching has been reported to be a viable way for achieving magnetization reversal in fs time scales. Among the mechanisms involved in such ultrafast, magnetization switching is the generation of large opto-magnetic fields by fs circularly polarized laser pulses. In this work, we seek to exploit plasmonic resonances at the interface between magnetic materials and plasmonic materials. The enhancement of the opto-magnetic field is obtained via the excitation of plasmons induced by laser pulses. Ideally, the magneto-plasmonic nanostructures should consist of magnetic films with strong Perpendicular Magnetic Anisotropy (PMA) and a plasmonic material with low optical losses. CoCrPt magnetic films and TiN plasmonic materials are chosen in this work as the components of the magneto-plasmonic nanostructures. CoCrPt films grown on TiN exhibit in-plane magnetization. This study aims to search for suitable ultrathin seed layers for the growth of CoCrPt films with strong PMA on TiN plasmonic materials. Suitable seed layers need to be no more than a few nm in thickness, as the generated opto-magnetic field is expected to be strongly decremented by the presence of a thick interlayer between TiN and CoCrPt. The optimal thickness of seed layers based on magnetic, optical, and opto-magnetic properties will be further explored. As shown in the preliminary results, the growth of CoCrPt films on (CoCrPt)Ta seed layers deposited on TiN exhibit PMA. Whereas PMA is weaker than that observed when CoCrPt is grown on thick Ta/Ru bilayers, the reported results pave the way for the growth of magnetic materials on photonic structures.

Date: Wednesday, January 22, 2020

Time: 1:30 P.M.

Place: ARMS 1109