MFM imaging of a HDD featuring PMR with magnetic domains being aligned parallel or antiparallel to the surface normal. (a) Sample piece as is and (b) after exposure to a strong DC magnetic field (μ 0 H > 1 T along the surface normal). In the latter case the ordered pitches "broke up" into more or less randomly aligned domains, reminiscent of former tracks. Note, (b) is affected by random noise more severely, with peak intensities being 5 times smaller than in (a). 

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Context 1

... illumination experiments were done on two atomic force microscopes (AFMs): an AIST CombiScope TM and an AIST-NT OmegaScope R TM at wavelengths of 532 nm and 785 nm, respectively. Both provided easy light access at an incident angle of γ = 70° and thus an elliptical laser spot (of around 2 × 6 µm 2 and 3 × 9 µm 2 at the sample surface for the 532 nm and the 785 nm laser, respectively). The laser beam di- ameter was measured optically (scattering on a rough sample) and by following the AIST TERS tip alignment routine (per- forming an objective scan around the tip and recording the phase signal). This is in agreement with theoretical predictions for the optical setup in use (focal length of focusing objective = 20.3 mm, aperture diameter = 6 mm): for a wavelength of 785 nm the calculated beam waist is w B = 3.4 μm and the FWHM of the Gaussian is w FWHM = 2.9 μm, assuming a spheri- cal beam under normal incidence (for 532 nm: w B = 2.3 μm and w FWHM = 2.0 μm). Furthermore, both AFMs were used for magnetic force microscopy (MFM) using Bruker MESPT- M MFM tips, allowing a resolution of features as small as 50 nm. For magnetic imaging two MFM modes were in use: stan- dard two-pass scans (50 nm lift from the topography measured on the first scan on second pass, 20 nm amplitude) and plane scans performed over a plane surface formed by interpolation of a representative number of points over the scan region and lifted 50 nm from the mean plane height, also performed at 20 nm amplitude. In both cases amplitude and phase signals were re- corded, whereas the individual image quality depended on the cantilever resonance frequency setting and the clearer image (phase or amplitude) is presented here. A moving average was applied to all phase/amplitude profiles for better visualization of relevant features. Two different commercial PMR 2.5" HDDs were used for sampling: a Seagate 1 TB/3-platter drive (GoFlex TM series) and a Toshiba 120 GB/1-platter drive. In preparation of laser writing of magnetic features, the platters were exposed to a strong uniform magnetic DC field of μ 0 H > 1 T. A comparison of an untreated platter piece and one after field exposure is shown in Figure 1a and Figure 1b, re- spectively. Although the DC field does not align the magnetiza- tion of all grains in the same direction, the surface breaks up into small domains of random order as shown in Figure 1b, and the signal peak intensity of local magnetic features is lowered by more than a factor of 2. This aided in the detection of weaker magnetic signals, with a favorable disposition to stray-fields antiparallel to the DC field, and thus created a more manage- able background. b) after exposure to a strong DC magnetic field (μ 0 H > 1 T along the surface normal). In the latter case the ordered pitches "broke up" into more or less randomly aligned domains, reminiscent of former tracks. Note, (b) is affected by random noise more severely, with peak intensities being 5 times smaller than in (a). Thermo-magnetic plot of the coercive field strength (blue), normalized to the room temperature value, indicating switching field requirements. Zero-field-cooled (ZFC) thermo- magnetization plot (red; µ 0 H = 0.01 T), also normalized to its room temperature value, indicating a Curie temperature of T C < 900 K. Note, the thermo- magnetization plot is largely ruled by the magnetization signal of the soft underlayer (SUL), however, at 900 K certainly both, the SUL and the recording layer, became ...

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... illumination experiments were done on two atomic force microscopes (AFMs): an AIST CombiScope TM and an AIST-NT OmegaScope R TM at wavelengths of 532 nm and 785 nm, respectively. Both provided easy light access at an incident angle of γ = 70° and thus an elliptical laser spot (of around 2 × 6 µm 2 and 3 × 9 µm 2 at the sample surface for the 532 nm and the 785 nm laser, respectively). The laser beam di- ameter was measured optically (scattering on a rough sample) and by following the AIST TERS tip alignment routine (per- forming an objective scan around the tip and recording the phase signal). This is in agreement with theoretical predictions for the optical setup in use (focal length of focusing objective = 20.3 mm, aperture diameter = 6 mm): for a wavelength of 785 nm the calculated beam waist is w B = 3.4 μm and the FWHM of the Gaussian is w FWHM = 2.9 μm, assuming a spheri- cal beam under normal incidence (for 532 nm: w B = 2.3 μm and w FWHM = 2.0 μm). Furthermore, both AFMs were used for magnetic force microscopy (MFM) using Bruker MESPT- M MFM tips, allowing a resolution of features as small as 50 nm. For magnetic imaging two MFM modes were in use: stan- dard two-pass scans (50 nm lift from the topography measured on the first scan on second pass, 20 nm amplitude) and plane scans performed over a plane surface formed by interpolation of a representative number of points over the scan region and lifted 50 nm from the mean plane height, also performed at 20 nm amplitude. In both cases amplitude and phase signals were re- corded, whereas the individual image quality depended on the cantilever resonance frequency setting and the clearer image (phase or amplitude) is presented here. A moving average was applied to all phase/amplitude profiles for better visualization of relevant features. Two different commercial PMR 2.5" HDDs were used for sampling: a Seagate 1 TB/3-platter drive (GoFlex TM series) and a Toshiba 120 GB/1-platter drive. In preparation of laser writing of magnetic features, the platters were exposed to a strong uniform magnetic DC field of μ 0 H > 1 T. A comparison of an untreated platter piece and one after field exposure is shown in Figure 1a and Figure 1b, re- spectively. Although the DC field does not align the magnetiza- tion of all grains in the same direction, the surface breaks up into small domains of random order as shown in Figure 1b, and the signal peak intensity of local magnetic features is lowered by more than a factor of 2. This aided in the detection of weaker magnetic signals, with a favorable disposition to stray-fields antiparallel to the DC field, and thus created a more manage- able background. b) after exposure to a strong DC magnetic field (μ 0 H > 1 T along the surface normal). In the latter case the ordered pitches "broke up" into more or less randomly aligned domains, reminiscent of former tracks. Note, (b) is affected by random noise more severely, with peak intensities being 5 times smaller than in (a). Thermo-magnetic plot of the coercive field strength (blue), normalized to the room temperature value, indicating switching field requirements. Zero-field-cooled (ZFC) thermo- magnetization plot (red; µ 0 H = 0.01 T), also normalized to its room temperature value, indicating a Curie temperature of T C < 900 K. Note, the thermo- magnetization plot is largely ruled by the magnetization signal of the soft underlayer (SUL), however, at 900 K certainly both, the SUL and the recording layer, became ...

Context 3

... illumination experiments were done on two atomic force microscopes (AFMs): an AIST CombiScope TM and an AIST-NT OmegaScope R TM at wavelengths of 532 nm and 785 nm, respectively. Both provided easy light access at an incident angle of γ = 70° and thus an elliptical laser spot (of around 2 × 6 µm 2 and 3 × 9 µm 2 at the sample surface for the 532 nm and the 785 nm laser, respectively). The laser beam di- ameter was measured optically (scattering on a rough sample) and by following the AIST TERS tip alignment routine (per- forming an objective scan around the tip and recording the phase signal). This is in agreement with theoretical predictions for the optical setup in use (focal length of focusing objective = 20.3 mm, aperture diameter = 6 mm): for a wavelength of 785 nm the calculated beam waist is w B = 3.4 μm and the FWHM of the Gaussian is w FWHM = 2.9 μm, assuming a spheri- cal beam under normal incidence (for 532 nm: w B = 2.3 μm and w FWHM = 2.0 μm). Furthermore, both AFMs were used for magnetic force microscopy (MFM) using Bruker MESPT- M MFM tips, allowing a resolution of features as small as 50 nm. For magnetic imaging two MFM modes were in use: stan- dard two-pass scans (50 nm lift from the topography measured on the first scan on second pass, 20 nm amplitude) and plane scans performed over a plane surface formed by interpolation of a representative number of points over the scan region and lifted 50 nm from the mean plane height, also performed at 20 nm amplitude. In both cases amplitude and phase signals were re- corded, whereas the individual image quality depended on the cantilever resonance frequency setting and the clearer image (phase or amplitude) is presented here. A moving average was applied to all phase/amplitude profiles for better visualization of relevant features. Two different commercial PMR 2.5" HDDs were used for sampling: a Seagate 1 TB/3-platter drive (GoFlex TM series) and a Toshiba 120 GB/1-platter drive. In preparation of laser writing of magnetic features, the platters were exposed to a strong uniform magnetic DC field of μ 0 H > 1 T. A comparison of an untreated platter piece and one after field exposure is shown in Figure 1a and Figure 1b, re- spectively. Although the DC field does not align the magnetiza- tion of all grains in the same direction, the surface breaks up into small domains of random order as shown in Figure 1b, and the signal peak intensity of local magnetic features is lowered by more than a factor of 2. This aided in the detection of weaker magnetic signals, with a favorable disposition to stray-fields antiparallel to the DC field, and thus created a more manage- able background. b) after exposure to a strong DC magnetic field (μ 0 H > 1 T along the surface normal). In the latter case the ordered pitches "broke up" into more or less randomly aligned domains, reminiscent of former tracks. Note, (b) is affected by random noise more severely, with peak intensities being 5 times smaller than in (a). Thermo-magnetic plot of the coercive field strength (blue), normalized to the room temperature value, indicating switching field requirements. Zero-field-cooled (ZFC) thermo- magnetization plot (red; µ 0 H = 0.01 T), also normalized to its room temperature value, indicating a Curie temperature of T C < 900 K. Note, the thermo- magnetization plot is largely ruled by the magnetization signal of the soft underlayer (SUL), however, at 900 K certainly both, the SUL and the recording layer, became ...