here and here.
Prior to this the densest standard data tape is LTO-6. The acronym stands for Linear Tape-Open. The technology originally developed in the late 1990s as more open standards alternative to the existing proprietary magnetic tape formats of that era. HP, IBM and Seagate founded the LTO Consortium to manage and license the not-quite-open LTO standard. First licensed in 2012 you can now buy one for $35. the LTO consortium continues to urge improvements in the standard, but future projects like the LTO-10 standard are only predicted to hold 48TB. I'll just quote the sony press release.
"This newly developed magnetic tape technology uses sputter deposition, a type of vacuum thin film forming technology, to generate multiple layers of crystals with a uniform orientation on a polymer film with thickness of less than 5 micrometers. Until now, when the sputter method was used to deposit a thin film of fine magnetic particles on a polymer film, roughness on the surface of the soft magnetic underlayer caused the orientation of the crystals in the underlayer above it to become non-uniform. This in turn caused non-uniform crystalline orientation and variations in the size of the magnetic particles (grain) in the nano-grained magnetic layer directly above the underlayer, and prevented increases in recording densities. By optimizing sputter conditions and independently developing a soft magnetic underlayer with a smooth interface, Sony has made it possible to minimize disparities in crystalline length and growth. This enabled Sony to create a nano-grained magnetic layer composed of fine magnetic particles with an average size of 7.7 nm."
It's amazing that magnetic tape was invented 87 years ago in Germany by Fritz Pfleumer. This process started with paper tape coated with ferric oxide (Fe2O3.) If that's a stretch, remember that magnetic tape was first used to record computer data in 1951 on the UNIVAC I. That's chronologically closer to Pfleumer than it is to us. Anyway, it's been a full year since the Sony announcement and they have yet to manufacture the tapes.