UC Riverside

The magnetic recording industry is keeping up with the ultra high demand of high capacity hard drives by improving the areal recording densities of these devices. Such imposing advancement in utilization and performance is due to successive scaling in the geometrical dimensions of the device. This progression has been truncated by the fundamental limit known as the superparamagnetic limit which occurs when bits of digital data are aggressively decreased that ambient heat demagnetizes them, leading to loss of the stored data.

To overcome this problem, the use of large magnetic anisotropy energy density alloys is compulsory, but the write fields that are required by these alloys are prohibitively large, rendering these media effectively unwritable. Fortunately, heat assisted magnetic recording (HAMR) enables the use of the smallest possible thermally stable grains, irrespective of the ultra-large intrinsic anisotropy. HAMR exploits the substantial drop of coercivity of ferromagnetic material to a level attainable by the magnetic writing head when the disk temperature is elevated close to its Curie level, consequently enhancing the areal density dramatically.

In this thesis, a theoretical and experimental study underlying the design of a heating element based on ultra-high-efficiency near-field optics suitable for extending areal densities beyond 1Tbit/in2 is presented. Near-field apertures are fabricated using focused ion beam milling and characterized via near-field optical microscopy. A breakthrough in the localization of adequate amount of heat into a 30 nm spot size is reported. HAMR demonstration is presented utilizing a customized spinstand tester, and the associated issues are thoroughly addressed.