Narrow Results

With the substantial increase in the amount of data, the mismatch between the processing speed of the hardware and the software results in the ‘Memory Wall’ problem. Processing-in-memory (PIM), in which the compute and memory units are integrated, can avoid frequent data transmission. Binary neural network (BNN) uses binary weights and activations instead of full-precision weights and activations in the convolutional neural network, which reduces computational complexity with minor influence on accuracy. In this paper, we used a one-step operation to write a pair of SOT-MRAM cells and verified the two basic operations in BNN: XNOR and bitcount. Then, we employed an external control circuit with FPGA and accomplished ‘I’ single-character recognition based on vector-matrix multiplication in the SOT-MRAM array.

Spin-orbit torque (SOT) plays an efficient and versatile role in electrical manipulation in spintronic devices at the nanoscale, which shows great promise for ultrafast and energy-efficient magnetic random-access memory (MRAM). To get high-performance SOT devices, their charge-to-spin conversion ratio must be sufficiently high and low current consumption is the desired one. Two-dimensional van der Waals (2D-vdW) materials possess strong tunability and spin-orbit coupling compared to conventional metals, which can efficiently achieve both things. This review covers a generalized introduction to SOT and its origin, their measurement techniques, SOTs observed in various 2D material-based heterostructures made of topological insulators (TIs), transition metal dichalcogenides (TMDs), and van der Waals (vdW) materials as they have excellent electronic properties down to their monolayer limit and ease of integration. Further, it covers the recent progress of SOT devices in each category, highlighting their potential for achieving high-performance and energy-efficient spintronic devices and their potential applications.

The manipulation and detection of antiferromagnetic (AFM) in exchange bias (EB)-based MRAM using spin-orbit torque (SOT) holds promise for developing highly reliable and ultrafast spintronic memory devices. However, the high switching current induced by the SOT-induced EB field remains a major drawback. Additionally, the mechanism behind the interaction between the EB field and the SOT remains unclear. To address this issue, we have introduced a thin layer of Mo between the AFM and ferromagnetic-free layers to tune the EB field and study the SOT-induced switching properties. Our findings indicate that when the SOT is dominant during short pulses of a few nanoseconds, Mo insertion can significantly reduce the EB field and decrease the SOT switching current, leading to a reduction in power consumption of these memories. This approach could open up new possibilities for optimizing EB-MRAM and improving our understanding of AFM electronics.