Characterization of C-apertures in a successful demonstration of heat-assisted magnetic recording

Abstract

An optical pump-probe setup was used to measure the coercivity change in a heat-assisted magnetic recording (HAMR) medium. The incident optical power required to attain the Curie temperature of the medium was determined by calculating its coercivity from BH loops under different illuminating laser powers through use of the Kerr signal in the pump-probe setup. The HAMR medium was then illuminated through an array of square and C-shaped nanoapertures so that the necessary laser power required for magnetic reversal could be compared to the bulk case. Magnetic force microscopy and Kerr microscopy revealed that C-apertures were able to permit heating of the magnetic medium and lower the coercivity to achieve magnetic reversal whereas the square apertures were not. The results show that aperture shape and design play a large role in HAMR head designs.

Graphene overcoats for ultra-high storage density magnetic media

“…The quality and uniformity of the samples are assessed by Raman spectroscopy 54 . Unpolarized Raman spectra are recorded at 514.5, as well as at 785 nm, close to the 850 nm used for HAMR writing tests 25 , 55 , with a Renishaw InVia spectrometer equipped with a Leica DM LM microscope and a ×100 objective with a numerical aperture 0.85. A 514.5 nm Raman spectrum of 1LG on Cu before the transfer is shown in Fig.…”

“… 25 , 55 , here we use an IR laser to examine the 1–4LG irradiation stability. To test whether 1LG can withstand HAMR conditions we consider 1LG transferred on L1 0 -FePt-based HDM 25 , 27 , 55 and on Si/SiO 2 . Reference 55 achieved T c at ~1.3 mW/μm 2 by optimizing aperture optics.…”

“…To test whether 1LG can withstand HAMR conditions we consider 1LG transferred on L1 0 -FePt-based HDM 25 , 27 , 55 and on Si/SiO 2 . Reference 55 achieved T c at ~1.3 mW/μm 2 by optimizing aperture optics. Reference 25 suggested using a laser power density ~10 7 W/cm 2 and ~0.35 × 10 7 W/cm 2 for FePt-based HDM.…”

Light Concentration by Metal-Dielectric Micro-Resonators for SERS Sensing

“…Recent development of the plasmonics provides the possibility to concentrate the light onto a nano-area. Metal nanoantennae and subwavelength apertures [219] are used to better increase the local electric field in the subwavelength volume. The optical field enhancement and concentration are achieved by excitation of surface plasmons [220,221].…”

“…The field distribution was simulated by using three FePt nanospheres with a diameter of 20.166667emnm located within in the apex’s vicinity of the stick (see Figure 34). For magnetic recording assisted by heat, FePt nanoparticles are mainly employed [219,232].…”