IBM and StorageTek are both forecasting terabyte-capacity cartridges. This requires that the read/write heads can place and detect the signals needed on the media. This media will contain many more but much narrower tracks. The magnetized areas on these tracks will also be much smaller. The quality of the media is crucial.

Because the magnetized areas are smaller and the tracks closer together, the read/write heads have to work with smaller, i.e. weaker, signals. To enable them to separate such signals from the neighbouring magnetized areas they have to be closer to the tape. This means that the tape has to be smoother. If a signal occurs in a depression it may be missed. If a bump is too high then it is broken off by the head and becomes potentially contaminating debris.

Fuji Film
Fuji Film is using Nanocubic technology. With this the tape media's base film has an non-magnetized layer underneath the magnetized layer. Fuji Film says the coating layers are ten times thinner than current technology. Two kinds of iron-based particles are used, both of the order of ten to the minus nine in size. This is the nanometre area.

A nanometre (nm) is 1,000 picometres which is 10 angstroms, one hundredth of a centimetre. Atoms may have a radius of between one quarter and three angstroms. The DNA helix has a 2nm diameter. Extreme ultra violet light has a wavelength of 40nm. Most wood smoke particles are smaller than 100nm.

The Fuji Film particles are less than 100nm in size. They are acicular ferromagnetic alloy and tabular ferromagnetic hexagonal barium ferrite.

In nanometre-scale coatings it is important that the particles are dispersed evenly throughout the coating. A polymer binding is used which helps create an even dispersion and a uniform density of particles across the coating layer.

Tera Angstrom technology is Imation's term for its super fine particle tape. The corporation says it uses a high-pressure - greater than 10,000 psi - jets to create its particles in what is called an impingement process. Again there is the base film layer, an intermediate layer and then the top magnetic coating.

In effect, particles are smashed into one another and break up into smaller fragments which are used for the coating. The tape media then passes through a high-temperature drying process in which magnetic coils in a chamber are used to orient the particles. There is also an even airflow, with low turbulence, to help dry the media.

Then the tape is passed through a set of ultra-smooth rollers to smooth the surface and improve the packing of the coating. This process is called calendering. The result is a surface with a height variation measured in angstroms. After this process the coated film is slit into individual ribbons and wound onto reels for mounting inside a cartridge.

With such media we can envisage between 1,000 and 2,000 tracks. Current media will have 500-600 tracks. The write track width shrinks from 15microns to 7-10microns. The read track width decreases also from 7microns to 3-5microns. (A micron is 1,000nm.)

The result of this can be seen in StorageTek's next-generation tape, the SDLT roadmap and the LTO 4 iteration. It is possible, indeed probable, that the LTO consortium is thinking about what follows on from LTO 4. It won't want to leave an opening into which SDLT can jump and increase its popularity with customers.

We might expect that all high-capacity tape drive manufacturers will use such media. Without it they simply may no longer be able to compete. This iteration of horizontally-laid particles may be the last before vertical recording is introduced, if that is possible with tape media.