Verification and Design of Position Matching Effect in MAMR Using Dual-FGL STO

We investigated the matching effect between a recording head with a spin-torque oscillator (STO) and a recording medium in microwave-assisted magnetic recording (MAMR). We equipped an STO with a dual-field generation layer (dual-FGL), whose oscillation had been experimentally demonstrated. Although the position alignment between the microwave field (
$H_{\mathrm {AC}}$
) distribution of the STO and the transition point in the medium is crucial for MAMR, our numerical simulations found that the previous dual-FGL STO provided a microwave field that shifted from the FGLs’ center toward the trailing shield (TS). We measured recording performance on multiple media to verify the shifted
$H_{\mathrm {AC}}$
distribution in the previous dual-FGL STO and confirmed an effective signal-to-noise ratio (SNR) improvement compared to a conventional medium by 3.5 dB in a media with small coercivity. We proposed the modification of the FGL’s thickness and stacking order to rearrange the
$H_{\mathrm {AC}}$
distribution, and recording areal density (AD) was simulated with the improved STO designs. Our results show that an appropriate combination of media and STO design, taking interaction with TS into consideration, provides improved AD with MAMR.