Direct Measurement of the Thermal Gradient in Heat Assisted Magnetic Recording

In heat assisted magnetic recording, the thermal gradient at the recording point determines the quality of the written transitions. We developed an experimental technique that enables us to find the thermal gradients in both the down- and the cross-track directions, where the laser power is modulated during the recording process. It is explained in detail how quantitative information on the gradients can be obtained from the measured data. It is found that strong heat-sinking of the media increases the thermal gradient and that the gradient measurement reacts sensitively to the shape of the thermal profile.