A special recording medium that has good thermal stability at room temperature is used in HAMR. When a focused optical beam is delivered onto its surface, the local medium is temporarily heated up to exceed its Curie temperature. This also lowers its coercivity to allow magnetic recording. When the local medium cools down, it becomes stable again to retain data.

Cost-intensive optics

Localized surface plasmon resonance could play an important role in HAMR by providing a highly focused optical spot for heating the recording medium within a small volume, thus facilitating the recording density. However, researchers are struggling with low-cost integrated optic designs that not only provide a better focused optical field, but also achieve higher efficiency to avoid reliability issues

Doubling recording density

International research collaboration between the University of Rochester in the United States and Swinburne University of Technology in Australia seeks to address such a dilemma. The scholars design an aluminum near field transducer based on a novel bow-tie structure, and engineer a highly integrated micro-nano-optics system for use in HAMR.

Using three-dimensional finite-difference time-domain simulation, they find that their design can generate a competitive optical spot size of 35 nm inside the magnetic medium at the wavelength of 450 nm. This corresponds to a recording density of up to 2 Tb/in2. At the same time it offers a much higher efficiency compared with previously reported designs that are mostly based on noble metals such as gold.

Remaining work on this project may include further optimization of the structure dimensions, device fabrication and characterization. Nevertheless, the researchers have demonstrated that aluminium can be a high-efficiency inexpensive plasmonic material for the development of HAMR technology, thereby providing a solution that might double the capacity of traditional hard disk drives.

More information can be found in the journal Nanotechnology 25 295202.

Further reading

Competing interactions and stepwise magnetization observed in Fe nanoparticle films (Aug 2013)
Large-area nanopatterning: structuring uniform hard magnetic nanodots on thin film (Aug 2011)
Magnetic recording creates complex nanoparticle patterns (May 2012)