Exploiting STT-MRAMs for Cryogenic Non-Volatile Cache Applications

This paper evaluates the potential of spin-transfer torque magnetic random-access memories (STT-MRAMs) operating at cryogenic temperatures. Our study was carried out at both circuit and architecture levels by exploiting experimental magnetic tunnel junction (MTJ) data and a CMOS technology that was fully characterized down to 77 K. As a main result of our analysis, we show that for medium to large sized cache architectures, STT-MRAMs outperform their six-transistor static random access memory (6T-SRAM) counterparts at 77 K in terms of both dynamic and static (leakage) power as well as read access latency, only underperforming in terms of write latency. For an 8 MB STT-MRAM cache, the read latency is improved by 2× along with a reduction of 45% and 30% in read and write energy, respectively, as compared to an SRAM implementation.