The magnetization configurations within the pole tip of the single-pole-type head have been examined through a micromagnetic computer simulation based on the Landau–Lifshitz–Gilbert equation. The aspect ratio, including the effect of the exchange length (Lex), was defined as the ratio of the throat height (Th) to the write-track width (Tww) and the thickness (Tp), which is given (Th×Lex)/(Tww×Tp). It was found that the magnetization configuration and the perpendicular component of remanent head field (Hr) are strongly dominated by this aspect ratio at any value of Tww. It was also found that there is a characteristic aspect ratio at which Hr starts to decrease. These results show that decreasing the aspect ratio is an effective way to reduce the intensity of the remanent head field.
The effects of longitudinal bias field, used for domain control on the magnetization distribution in a magnetoresistive (MR) film, have been investigated by computer simulation. The longitudinal bias field was generated by an exchange-coupled antiferromagnetic or permanent magnetic film formed on the MR film outside the sensing region. It was assumed that the magnetization in the part of the MR film on which the bias-generating films were formed was fixed along the easy axis. The spatial sensitivity of the MR film along the track width was evaluated by calculating the dependence of the resistance change on the position of a narrow track recording medium. It was found that the resistance change in the MR film with the anti-ferromagnetic film was roughly twice as large as the change in the film with the permanent magnetic film. The asymmetric sensitivity profile with respect to reflection about the track width mid-plane was also obtained. The asymmetry in the track sensitivity profile was found to be caused by three factors: asymmetric magnetization distribution about the track width mid-plane due to the transverse bias field, the difference in angular changes in the magnetization direction in the left and right regions facing the recording medium, and anisotropic flux propagation in the MR film.
Single-pole writers and tunneling magnetoresistive (TMR) readers for 140-Gb/in 2 perpendicular recording were fabricated and their recording performance was tested. Data erasure, which is observed as write instability in a repeated read-write operation, can be suppressed by combining a laminated pole and low throat height. Fe-Co/Ni-Cr laminated film was used to reduce the remanent magnetization of the main pole after patterning. Narrow track writers with a 120-nm-wide trapezoidal pole showed a good write ability of 30 dB or more in overwrite for media with high coercivity of up to 7 kOe. Also, negligibly small skew writing was confirmed. TMR heads with a sensor width of 85 nm and a head resistance of 250 showed approximately 30 dB of head signal-to-noise ratio (SNR). A potentially higher SNR with a higher operating voltage was suggested from a measured output versus sensing current curve. Calculations showed that the side reading was suppressed in a side-shielded design. A 10% amplitude width of the microtrack profile of a 100-nm-wide reader was reduced from 198 to 162 nm by applying the side shields.
Sugarcane is essential for global sugar production and its compressed juice is a key raw material for industrial products. Sugarcane juice includes various metabolites with abundances and compositional balances influencing product qualities and functionalities. Therefore, understanding the characteristic features of the sugarcane metabolome is important. However, sugarcane compositional variability and stability, even in pretreatment processes for nuclear magnetic resonance (NMR)-based metabolomic studies, remains elusive. The objective of this study is to evaluate sugarcane juice metabolomic variability affected by centrifugation, filtration, and thermal pretreatments, as well as the time-course changes for determining optimal conditions for NMR-based metabolomic approach. The pretreatment processes left the metabolomic compositions unchanged, indicating that these pretreatments are compatible with one another and the studied metabolomes are comparable. The thermal processing provided stability to the metabolome for more than 32 h at room temperature. Based on the determined analytical conditions, we conducted an NMR-based metabolomic study to discriminate the differences in the harvest period and allowed for successfully identifying the characteristic metabolome. Our findings denote that NMR-based sugarcane metabolomics enable us to provide an opportunity to collect a massive amount of data upon collaboration between multiple researchers, resulting in the rapid construction of useful databases for both research purposes and industrial use.
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