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Peng C.,Seagate Technology
Journal of Applied Physics | Year: 2012

An optical near-field transducer composed of a rectangular patch and a protruded peg has been numerically studied for heat-assisted magnetic recording. This transducer strongly interacts with a planar solid immersion focusing field and efficiently couples optical energy into a recording medium in a region determined by the peg cross-section. The transducer is excited through the electric field predominantly normal to its edges. The optimal size of the rectangular patch is found to be a half-wave optical antenna in height and between half-wave and full-wave in width. © 2012 American Institute of Physics.

Peng C.,Seagate Technology
Optics Express | Year: 2015

Focal point shift in a solid immersion mirror of a high numericalaperture is experimentally demonstrated with a scanning near-field optical microscope. The solid immersion mirror focuses light by a two-dimensional parabolic reflective surface integrated in a planar waveguide. The focal point shifts inward along the optical axis for metallized surface. The amount of shift from its geometrical node depends on the wavelength of the incident light and is determined to be roughly one-fifth of the wavelength. © 2015 Optical Society of America.

Fan Y.,College of William and Mary | Smith K.J.,College of William and Mary | Lupke G.,College of William and Mary | Hanbicki A.T.,Washington Technology | And 4 more authors.
Nature Nanotechnology | Year: 2013

The ferromagnet/oxide interface is key to developing emerging multiferroic and spintronic technologies with new functionality. Here we probe the Fe/MgO interface magnetization, and identify a new exchange bias phenomenon manifested only in the interface spin system, and not in the bulk. The interface magnetization exhibits a pronounced exchange bias, and the hysteresis loop is shifted entirely to one side of the zero field axis. However, the bulk magnetization does not, in marked contrast to typical systems where exchange bias is manifested in the net magnetization. This reveals the existence of an antiferromagnetic exchange pinning layer at the interface, identified here as FeO patches that exist even for a nominally 'clean' interface. These results demonstrate that atomic moments at the interface are non-collinear with the bulk magnetization, and therefore may affect the net anisotropy or serve as spin scattering sites. We control the exchange bias magnitude by varying the interface oxygen concentration and Fe-O bonding. © 2013 Macmillan Publishers Limited. All rights reserved.

Peng C.,Seagate Technology
Applied Physics Letters | Year: 2014

Surface-plasmon resonance of a lollipop near-field transducer integrated in a planar solid immersion mirror for heat-assisted magnetic recording has been characterized by measuring the amount of transmitted light in the polarization state orthogonal to the illumination in the far field. This resonance is compared to that probed with a photothermal measurement in near-field. The difference in peak wavelength between the two measures is only about 20nm. © 2014 AIP Publishing LLC.

Hong S.W.,University of Massachusetts Amherst | Gu X.,University of Massachusetts Amherst | Huh J.,Yonsei University | Xiao S.,Seagate Technology | Russell T.P.,University of Massachusetts Amherst
ACS Nano | Year: 2011

We report the fabrication of ultradense circular nanolines of block copolymer (BCP) microdomains over macroscopic areas. These lines were generated by the directed self-assembly (DSA) of BCPs on the topographically patterned substrates, where the trenches with circular shape are patterned on a flat substrate. The width of the trench and the distance between trenches are varied for commensurability issues, and difference BCPs are used to demonstrate the generality of this strategy. When a commensurability condition is satisfied, BCPs on the topographically patterned substrates undergo a DSA with solvent annealing, resulting in a flat film with an areal density amplification of the circular patterns over large areas. The methodology described here may provide an easy approach to high densities of circularly shaped nanopatterns for data storage device manufacturing. © 2011 American Chemical Society.

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