The Pursuit of Saving Energy Consumption of Memory Systems by MRAMs, from STT-MRAM to Voltage-Control Spintronics Memory (VoCSM)

MRAM has been developed since 1980s until now with several ups and downs. The ultimate purpose is to realize non-volatile working memories to save energy consumption of conventional volatile working memories such as SRAM and DRAM. However all of non-volatile memories including MRAM have been facing a dilemma of non-volatility and high energy consumption in their active mode because non-volatility has led to large writing-energy consumption, $E_{w}$. As a result, they have been used as data storages and none of them overcame the historical dilemma for busy applications. This is the one of the reasons why MRAM has not had big markets so far. Recently, the possibilities of overcoming the dilemma were demonstrated by both STT-MRAM and VoCSM [1], [2]. STT has better maturity but less room for further improvement. On the other hands, VoCSM has poor maturity but better potentials in terms of higher writing efficiency and better endurance [3]. In this talk, STT technologies and VoCSM technologies is reviewed with respect to saving energy consumption and remaining issues for VoCSM will be discussed at the conference.