Effect of RE-TM underlayer on the microstructure of TbFeCo memory layer for high-density magneto-optical recording

A magneto-optical (MO) medium has been investigated as high-density data storage. This MO medium sputtered from an intermetallic compound alloy target has advantages for mass production. However, it may have some difficulties for advanced high-density recording due to the controllability of the magnetic properties. In order to use the mass-production advantages of this MO medium, the intrinsic magnetic properties of its film must be clarified. This paper investigates the relationship between MsHc and the magnetic underlayers, which are controlled by the film´s microstructure. It is found that the MsHc of the memory layer can be increased by controlling the first magnetic underlayer; furthermore, the arranged microcolumnar structure in the memory layer is also found to be closely related to the underlayer. As a result, as much as 1.8×10⁶ erg/cm³ MsHc can be obtained even by sputtering from an alloy target. Adopting this film for the memory layer in a domain wall displacement detection system is promising approach for high-density recording that features reliably written tiny marks.