Near-Field Optics for Heat-Assisted Magnetic Recording (Experiment, Theory, and Modeling)
One application of near-field transducers (NFT) is in heat-assisted magnetic recording (HAMR). HAMR is similar to conventional magneto-optical (MO) recording in that the data are stored in magnetic bits on a disk by heating the area of the bit with a laser beam in the presence of an external field to set the magnetic orientation of the bit as it cools. The optical head in conventional MO recording is mounted on an actuator and optical feedback signals are used to maintain a constant spacing between the head and the recording medium, which is generally on the order of tens or hundreds of nanometers. Also, for conventional MO recording the applied magnetic field is very small (approximately 0.02 T), typically generated by a large fixed external magnet, and the laser energy rather than the magnetic field is modulated with the input data stream. On the other hand, for HAMR the integrated optical–magnetic head is mounted on a slider, which flies over the surface of the recording medium at 10 nm or less. The applied field for HAMR is highly localized, very large in magnitude (up to 1 T or more), and generated by a miniature recording pole positioned within tens of nanometers of the optical spot. For HAMR the magnetic field from the pole is modulated with the input data stream, while the laser energy on the medium can remain constant.
KeywordsLocalize Surface Plasmon Resonance Resonance Wavelength Scattered Field Finite Difference Time Domain Poynting Vector
We would like to acknowledge many useful conversations with our Seagate colleagues Ed Gage, Eric Jin, Terry McDaniel, and Chubing Peng during the course of this work.
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