Progression of transition metal nitrides towards stable plasmonic materials for heat assisted magnetic recording

Abstract

Heat Assisted Magnetic Recording (HAMR) is the next step in hard disk drive technology to quench the world’s ever-increasing demand for data storage. This technology can currently attain areal densities up to 2 Tb in-2. Plasmonic materials are a key factor in enabling this technology but require chemical and thermal stability for use in a Near Field Transducer (NFT), up to 300 ̊C. Current materials include the noble metals, due to their excellent plasmonic properties, but these have poor thermal stability.

Seagate Technology sponsored this PhD and provided a broad definition of the scope involved for finding alternative plasmonic materials for HAMR NFTs. This Thesis focuses on the Group IV nitrides and their role in addressing current stability issues with HAMR and other high temperature applications.

The inclusion of a Cr90Ru10 seed layer, TMN/CrRu/SiO2 is shown to promote highly textured growth of the (200) phase in all metal nitride systems studied and has informed on the move away from non-technological substrates within a reduced thermal budget. All binary nitrides were shown to have improved corrosion resistance in atmospheric and vacuum anneals compared with noble metals. TiN and ZrN were found to have the most interesting optical properties at 1310 nm and 1550 nm for HAMR devices. It was found that ZrN/CrRu/SiO2 presented the best optical properties of the Group IV binary nitrides but was the most prone to corrosion after high temperature annealing.

The research investigated improving the thermal stability of ZrN through doping. ZrN thermal stability is shown to improve when doped with B and Hf. It is found that increasing dopancy of B and Hf improves the corrosion resistance of ZrN, at the cost of optical properties. Interestingly it is found that doping HfN with Zr, in a ZrHfN/CrRu/ SiO2 system, promotes highly textured growth of HfN thin films.

Thesis is embargoed until 31 July 2026.

Date of Award	Jul 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	EPSRC Centre for Doctoral Training in Photonic Integration and Advanced Data Storage & Seagate Technology LLC
Supervisor	Robert Bowman (Supervisor)