Abstract: The emergence of embedded magnetic random-access memory (MRAM) provides an unprecedented opportunity to develop unconventional computing architectures, which go far beyond using MRAM as a mere replacement for existing memory solutions (e.g., embedded Flash or SRAM).

This talk will consist of two parts: First, we review the current state of development of ferromagnet-based MRAM, which uses current-induced spin-transfer torque (STT) to switch the magnetic state. We then discuss how emerging device concepts based on new physics and new materials may enable significant advances beyond today’s STT-MRAM: (i) As an example of new materials, we examine memory devices based on antiferromagnetic (AFM) materials, which may offer advantages such as picosecond switching, improved scalability, and immunity to external magnetic fields. We review recent progress in manipulating the Néel vector of such materials by current-induced spin-orbit torque (SOT) and discuss perspectives for their further development. (ii) As an example of new physics, we discuss electric-field-controlled MRAM devices that utilize the voltage-controlled magnetic anisotropy (VCMA) effect for switching, and present recent results on developing the first VCMA-MRAM devices with sub-1V write voltage.

Second, we will discuss how appropriately designed stochastic MRAM cells with low retention time can be used to fulfill unconventional roles within a computing system, notably as electrically controlled stochastic bitstream (SBS) generators. We then discuss the application of such MRAM-based SBS generators to true random number generation and stochastic computing (SC) and present our recent results on the implementation of an SC-based artificial neural networks and physically unclonable functions using a series of stochastic MRAM cells. Finally, we then show examples of how a network of stochastic MRAM bits with appropriately designed control/readout circuitry – referred to as probabilistic (p-) bits – can be used to solve difficult optimization problems..