Grazing-incidence optical magnetic recording with super-resolution.

Heat-assisted magnetic recording (HAMR) is often considered the next major step in the storage industry: it is predicted to increase the storage capacity, the read/write speed and the data lifetime of future hard disk drives. However, despite more than a decade of development work, the reliability is still a prime concern. Featuring an inherently fragile surface-plasmon resonator as a highly localized heat source, as part of a near-field transducer (NFT), the current industry concepts still fail to deliver drives with sufficient lifetime. This study presents a method to aid conventional NFT-designs by additional grazing-incidence laser illumination, which may open an alternative route to high-durability HAMR. Magnetic switching is demonstrated on consumer-grade CoCrPt perpendicular magnetic recording media using a green and a near-infrared diode laser. Sub-500 nm magnetic features are written in the absence of a NFT in a moderate bias field of only µ0H = 0.3 T with individual laser pulses of 40 mW power and 50 ns duration with a laser spot size of 3 µm (short axis) at the sample surface - six times larger than the magnetic features. Herein, the presence of a nanoscopic object, i.e., the tip of an atomic force microscope in the focus of the laser at the sample surface, has no impact on the recorded magnetic features - thus suggesting full compatibility with NFT-HAMR.

Directed self-assembly of nanorod networks: bringing the top down to the bottom up.

Self-assembled electrodeposited nanorod materials have been shown to offer an exciting landscape for a wide array of research ranging from nanophotonics through to biosensing and magnetics. However, until now, the scope for site-specific preparation of the nanorods on wafers has been limited to local area definition. Further there is little or no lateral control of nanorod height. In this work we present a scalable method for controlling the growth of the nanorods in the vertical direction as well as their lateral position. A focused ion beam pre-patterns the Au cathode layer prior to the creation of the anodized aluminium oxide (AAO) template on top. When the pre-patterning is of the same dimension as the pore spacing of the AAO template, lines of single nanorods are successfully grown. Further, for sub-200 nm wide features, a relationship between the nanorod height and distance from the non-patterned cathode can be seen to follow a quadratic growth rate obeying Faraday's law of electrodeposition. This facilitates lateral control of nanorod height combined with localized growth of the nanorods.