Valley-Coupled-Spintronic Non-Volatile Memories with Compute-In-Memory Support

Abstract

In this work, we propose valley-coupled spin-hall memories (VSH-MRAMs) based on monolayer WSe2. The key features of the proposed memories are (a) the ability to switch magnets with perpendicular magnetic anisotropy (PMA) via VSH effect and (b) an integrated gate that can modulate the charge/spin current (IC/IS) flow. The former attribute results in high energy efficiency (compared to the Giant-Spin Hall (GSH) effect-based devices with in-plane magnetic anisotropy (IMA) magnets). The latter feature leads to a compact access transistor-less memory array design. We experimentally measure the gate controllability of the current as well as the nonlocal resistance associated with VSH effect. Based on the measured data, we develop a simulation framework (using physical equations) to propose and analyze single-ended and differential VSH effect based magnetic memories (VSH-MRAM and DVSH-MRAM, respectively). At the array level, the proposed VSH/DVSH-MRAMs achieve 50%/ 11% lower write time, 59%/ 67% lower write energy and 35%/ 41% lower read energy at iso-sense margin, compared to single ended/differential (GSH/DGSH)-MRAMs. System level evaluation in the context of general purpose processor and intermittently-powered system shows up to 3.14X and 1.98X better energy efficiency for the proposed (D)VSH-MRAMs over (D)GSH-MRAMs respectively. Further, the differential sensing of the proposed DVSH-MRAM leads to natural and simultaneous in-memory computation of bit-wise AND and NOR logic functions. Using this feature, we design a computation-in-memory (CiM) architecture that performs Boolean logic and addition (ADD) with a single array access. System analysis performed by integrating our DVSH-MRAM: CiM in the Nios II processor across various application benchmarks shows up to 2.66X total energy savings, compared to DGSH-MRAM: CiM.

References in corpus (12)

• Spin torque switching with the giant spin Hall effect of tantalum
• Magnetic switching by spin torque from the spin Hall effect
• Spin transfer torque devices utilizing the giant spin Hall effect of tungsten
• Switching of perpendicular magnetization by spin-orbit torques in the absence of external magnetic fields
• Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal Deposition
• Threshold current for switching of a perpendicular magnetic layer induced by spin Hall effect
• Nonlocal Charge Transport Mediated by Spin Diffusion in the Spin-Hall Effect Regime
• Thermally activated switching of perpendicular magnet by spin-orbit spin torque
• S2DS: Physics-Based Compact Model for Circuit Simulation of Two-Dimensional Semiconductor Devices Including Non-Idealities
• DSTT-MRAM: Differential Spin Hall MRAM for On-chip Memories
• Direct Observation of Valley Coupled Topological Current in MoS${}_2$
• From materials to systems: a multiscale analysis of nanomagnetic switching

Cited by in corpus (3)

• Multi-frequency Data Parallel Spin Wave Logic Gates
• FAT: An In-Memory Accelerator with Fast Addition for Ternary Weight Neural Networks
• Connecting physics to systems with modular spin-circuits