I remember hearing about MRAM while I was studying Materials Engineering at uni, also mentioned was Phase change memory, which worked off of a phase change between Crystalline and amorphous states in a glass material did anything ever progress with this technology? It sounded super interesting at the time.
I'm very far from an expert in this field, sorry. PCM (and other resistive memories) are definitely still a thing, though - they've been used for in-memory computation, doing vector-matrix multiplications directly in the memory cells and thus saving massive amounts of die area over using separate CMOS logic, so they're probably going to replace on-die SRAM for some applications.
