Signal to noise ratio scaling and density limit estimates in longitudinal magnetic recording

Recording processes in perpendicular patterned media using longitudinal magnetic recording heads

“…Once the grains become 10 nm, thermal fluctuations can flip the magnetization orientation of each grain on a time scale shorter than the ten years required for a standard hard drive use. Current media was initially predicted to show signs of thermal instability at densities around 50 Gb/in [1], [2], and experimental evidence of this effect has been reported [3], [4].…”

Writing and reading of single magnetic domain per bit perpendicular patterned media

“…The fabrication and characterization of arrays of individual magnetic single domain columnar particles with a size and spacing that will support bit densities of ϳ100 Gbits/in. 2 have been demonstrated. [9][10][11] The effects of local magnetic probes on these particles have been observed, 12 but effective nonvolatile magnetic storage including controlled writing has not yet been demonstrated.…”

“…Extensive recent theoretical analysis 1,2 supports ϳ40 Gbits/in. 2 , but casts severe doubts on achieving stable storage at densities of 100 Gbits/in. 2 due to the thermal instability of the distribution in size of the individual magnetic grains which behave as superparamagnetic particles.…”

“…2 , but casts severe doubts on achieving stable storage at densities of 100 Gbits/in. 2 due to the thermal instability of the distribution in size of the individual magnetic grains which behave as superparamagnetic particles. Two high density magnetic storage schemes, both based on lithographically defined single domain magnet arrays, have been proposed to solve the superparamagnetic limit problem.…”

“…For practical media these designs must maintain the necessary signal to noise ratio, while avoiding the onset of the superparamagnetic limit for areal densities beyond 100 Gbits/in. 2 .…”