2019 年 3 巻 1 号 p. 1-6
Bit patterned media is a possible candidate for developing next-generation ultra-high-density data storage, therefore, the importance of shape, of techniques for fabricating magnetically monodisperse dots, and of research on materials that have high uniaxial magnetocrystalline anisotropy energy such as L10-FePt is increasing. Furthermore, although the magnetic characterization of each isolated patterned dot is a crucial matter, there is a fundamental difficulty in measuring infinitesimal magnetic moments. On the basis of the idea of estimating the magnetic properties of a single dot by measuring several hundred million monodisperse dots, we investigated a process for fabricating monodisperse FePt dots and a magnetization process. In this report, we propose a novel fabrication procedure that consists of a combination of pre-patterning Pt/Fe film and post-annealing with rapid thermal annealing. Pt/Fe dots with a pitch of 100 nm and thickness of 3.75 nm were pre-patterned by using an electron beam lithography technique and rapidly heated up to 800℃, which lead to a lower dispersal of dots that was promoted by a hard-magnetic property. Under a Fe-rich composition condition for Fe60Pt40, 90% of the FePt dots showed a coercive force of over 15 kOe.
