The challenge for these usurpers to NAND is getting near to NAND's density - now at 64Gbit.
The densest commercial phase change chip ever sold is 128Mbit. Last week's announcement by IBM of a two-bit-per-cell phase change helps, but doesn't get phase-change anywhere near the memory mainstream.
Toshiba and Hynix will focus on the spin-transfer torque approach to MRAM - a relatively new development in the long MRAM saga which has seen initiatives from: IBM, Infineon, Honeywell, NEC, Cypress, Motorola/Freescale which spun off their MRAM team to Everspin Technologies, Sony, Hitachi, Renesas, Samsung, Micron and Crocus.
MRAM densities have so far been even behind phase-change:
Infineon produced a 16Mbit MRAM prototype in 2004;
Honeywell offered a 1Mbit device for sale in 2005;
Toshiba and NEC demo-ed a 16Mbit device in 2006;
Freescale were selling a 4Mbit MRAM for $25 in 2006;
Hitachi and Toshiba showed off a 32Mbit device in 2009 and, the following year, last year, showed a multi-level cell MRAM.
While NAND is halfway to Tbit density, MRAM still hasn't migrated from the Mbit level.
Hynix, nonetheless, seems excited by the technology. "MRAM is a rare gem full of exciting properties," enthuses Hynix CEO Oh Chul Kwon.