Magnetic Data Storage: Past Present and Future

Abstract

The design of media, heads, positioning systems and data detection and coding techniques for various generations of magnetic recording systems are discussed. We will start with current systems, such as longitudinal hard disc and tape. Next we will discuss the near future, where perpendicular recording (thicker films, higher stray fields) will address the problem of thermal stability. In the third section we will give an outlook on future developments (patterned media, thermally assisted recording, self assembled arrays of nanoparticles and probe storage).

Self-Assembled Three-Dimensional Non-Volatile Memories

“…The growth in hard disk data density fluctuates between 40% and 100% per year. Predictions are that magnetic storage is limited to data densities of about 10 Tb/in 2 [5], which is another eight years from now at a growth rate of 40%. Probe storage technology [6] offers the possibility to increase the data density all the way up to one bit per atom data storage [4].…”

Properties of magnetic nanodots with perpendicular anisotropy

“…The proposed applications of magnetic nanodots include their use in patterned magnetic recording media 14 , as elements in magneto-resistance random access memories (MRAM's) 15,16 , spin transfer nanooscillators (STNO's) [17][18][19] and nanoscopic agents for cancer treatment 20 . The different magnetic configurations, and consequently the large variation in the magnetic properties observed in nanodots as a function of dimensions, underline the interest in the study of diagrams (phase diagrams) mapping the parameter space where a given magnetic behavior is to be expected.…”

Memory and aging effects in interacting sub-10 nm nanomagnets with large uniaxial anisotropy

“…Grained nanomagnets with large uniaxial anisotropy are essential to modern magnetic data storage. For typical CoCrPtB media, usual average grain sizes must be about 10nm to keep magnetic stability of 10 years at room temperature [19]. In the case of CoCrPt-oxide media for perpendicular recording, dominant inter-grain interactions are weak antiferromagnetic (AFM) couplings and average grain size can be 8nm or smaller for the same stability [19].…”

“…For typical CoCrPtB media, usual average grain sizes must be about 10nm to keep magnetic stability of 10 years at room temperature [19]. In the case of CoCrPt-oxide media for perpendicular recording, dominant inter-grain interactions are weak antiferromagnetic (AFM) couplings and average grain size can be 8nm or smaller for the same stability [19]. Such average size can even be reduced down to 3nm or smaller when FePt in the L1 0 phase is used as data storage media, because its magnetocrystalline anisotropy reaches to 44 meV/nm 3 [19].…”