The transition from longitudinal to perpendicular recording

Abstract

After more than 30 years of research, hard disk drives using perpendicular recording are finally commercially available. This review is a follow-up of a review written in 1999 and addresses the basic physics of perpendicular recording with special emphasis on the read and the write process and the magnetic aspects of the recording media. The paper also surveys various technical difficulties which prevented an earlier implementation of perpendicular recording. The paper closes with a short overview of alternative technologies that allow even higher storage densities.

Large-area patterning of sub-100 nm epitaxial L1 FePt dots array via nanoimprint lithography

“…The head writing field has a theoretical upper limit of 24 kOe due to the intrinsic nature of pole material. 18 In practice, owing to the head design and leakage of magnetic flux, this field could be even smaller, 37 and it is reasonable to assume the short-time head field to be 14 kOe. 38 Nevertheless, the sub-100 nm dots array demonstrated here could fit well into the current writing capability in magnetic recording.…”

“…In addition to the cost considerations, a too-thick magnetic media would trigger incoherent reversal by thermally injecting a perpendicular DW into the column. Richter argued 18 that the critical thickness, L T , is determined by E dw = E coh ( * ) , where domain wall energy E dw = πD 2 √ AK u is comparable to the energy barrier for coherent rotation…”

“…It has been reported that any dot shape fluctuation only contribute a second-order disturbance and can be neglected. 17 However, the dot size fluctuation is predicted to be critical 18 and narrow distribution (dot-size standard deviation, σ < 10%) is required for densities larger than 1Tb/in 2 . 6 One promising approach is nanoimprint lithography (NIL), 19 with advantages of high resolution, high throughput, low cost, and wafer scale fabrication.…”

Time-resolved scanning Kerr microscopy of flux beam formation in hard disk write heads

“…The write head is designed to maximize the available write field while minimizing erase after write errors and wide area track erasure. 5 It was first suggested by Mallary in 1985 that magnetic flux was conducted through structures similar to hard disk write heads by a process of small angle rotation of the magnetization, rather than by domain wall motion. 6 This leads to the formation of a narrow "beam" of flux along the central symmetry axis of the write head, a highly desirable property for generating both the strongest and most spatially uniform write field at the pole tip.…”

Performance Evaluation of Skewed Read-Head for Shingled Magnetic Recording

“…If the head is skewed, it is possible to complement the performance by positioning the two heads at the center of the current track. Interference, ITI) 역시 심각한 문제가 되었다 [1][2][3][4][5][6][7][8][9][10][11] .자기기록 장치에서 리드헤드가 트랙을 따라 돌면서 데이터를 읽을 때, 물리적인 영향으로 리드헤드가 방 향이 틀어 질 수 있다 [12,13] . 그림 1은 이러한 경우를 그림으로 나타냈다.…”