In heat assisted magnetic recording (HAMR), optical near field transducer (NFT) is a key
component. Au is currently used as NFT material because of its strong surface plasmon effect. Due
to the soft property of Au material, reliability of Au NFT becomes a key issue for realizing HAMR
production. In this paper, the possibility of alternative materials, including transition metal nitrides
(TMNs) and transparent conducting oxides (TCOs) to replace Au is studied. The results show that
all of the listed TMN and TCO materials can meet the mechanical requirements at room
temperature in terms of hardness and thermal expansion. An optical model, which includes optical
waveguide, NFT and FePt media, is used to simulate NFT performances. The results indicate that
the resonant wavelengths for NFT with TCO materials are longer than 1500 nm, which is not
suitable for HAMR application. TMN materials are suitable for NFT application at wavelength
band of around 800 nm. But the NFT efficiency is very low. ZrN is the best material among TMN
materials and the efficiency of ZrN NFT is only 13% of the Au NFT’s efficiency. Reducing
refractive index (n) and increasing extinction coefficient (k) will both lead to efficiency increase.
Increasing k contributes more in the efficiency increase, while reducing n has a relatively low NFT
absorption. For materials with the same figure of merit, the NFT with larger k material has higher
efficiency. Doping materials to increase the material conduction electron density and growing film
with larger size grain may be the way to increase k and reduce n.
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Copyright (2015) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 117, 17C112 (2015) and may be found at http://dx.doi.org/10.1063/1.4908029.