Study on nanoscale patterning using ferro-antiferromagnetic transition in [001]-oriented L1 FePtRh film

Abstract

A bit patterning process using the ferromagnetic (FM)-antiferromagnetic (AF) transition in [001]-oriented L10 FePt1-xRhx films was investigated. First, the composition (x) dependence of magnetization (Ms) and magnetocrystalline anisotropy (Ku) of the films was studied. The films with 0 ≤ x ≤ 0.32 showed ferromagnetism (800 ≤ Ms ≤ 1100 emu/cm3) with a high magnetocrystalline anisotropy (1.7 × 107 ≤ Ku ≤ 7.0 × 107 erg/cm3), and the films with 0.34 ≤ x ≤ 0.40 showed antiferromagnetism. The composition of x = 0.34 was the threshold of the FM-AF transition. Next, the FM-AF transition was applied for bit patterning. Atomic diffusion was used for modifying the composition. Only the magnetic phase of the area whose composition crossed the threshold changed abruptly to the FM phase. FM dots with sizes (D) of 20 ≤ D ≤ 1000 nm were observed in the AF matrix by magnetic force microscopy. The dots with D > 100 nm formed multidomain structures, and the dots with D ≤ 100 nm formed a single-domain structure.

Fabrication of [001] L1-FePtRh ferro-antiferromagnetic pattern by flat-patterning method

“…The first two methods involve the removal of the material between dots or the assembly of the particles, which leads to non-uniformity in the height of the disk surface and causes a head-floating problem for nearcontact recording. 1 However, in the last method, an FM film undergoes local changes to a soft magnetic, 5 paramagnetic (PM), 6 or antiferromagnetic (AF) 7 phase without surface asperity by ion irradiation or atomic diffusion.…”