Spingate announced that they invented a multi-bit Spin-RAM, which can store two bits per MTJ. It uses magnetic materials with perpendicular anisotropy and has a cell size of 4F2, which is the smallest currently reported in the industry. This kind of memory can provide a density of about 160 Gbits/in2 (0.257 Gbit/mm2) at 45 nm. They say their design has excellent thermal stability, and so can scale down to 10 nm.
Spingate's Spin-RAM uses the company's proprietary hybrid write mechanism based on a simultaneous application of a spin-polarized current and a bias magnetic field. The hybrid write mechanism provides the Spin RAM with a high switching speed (about 1 ns or less), low density of the spin-polarized current (about 106 A/cm2 or less), excellent endurance (about 1015 or above) and error rate. Spingate says that it can be smoothly arranged in a 3D architecture (without additional layers or selection transistors), and 1 Tbits/in2 can be achieved at 25 nm (with only two layers of MTJ) or at 18 nm (in a 2D architecture).
If Spingate is successful in commercializing this technology, it could enable an MRAM device that can compete in price with DRAM, Flash and even HDDs - and replace all three memory technologies. We'll have to wait and see how this develops of course!