A Novel P-bit Unit Based on VGSOT-MTJ for Reconfigurable Ising Machine With Fully Parallel Spin Updating Design

The spin-based probabilistic bit (p-bit) built on magnetic tunnel junction (MTJ) provides a low power and low overhead solution for building high performance Ising machine (IM). In this work, we propose a novel p-bit device that integrates a voltage-controlled magnetic anisotropy (VCMA) MTJ biased by spin-orbit torque (SOT) voltage. The proposed p-bit achieves an energy consumption of approximately 33fJ/bit per operation. A synchronous Ising network utilizing this device demonstrates rapid convergence to near-ground-state solutions when solving a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${13}\times {26}$ </tex-math></inline-formula>-vertex Max-Cut problem in simulation. Furthermore, a reconfigurable IM architecture, realized through the coupling of MTJ array, enables an all-spin Ising system capable of addressing various combinatorial optimization problems (COPs). The proposed IM system also exhibits functional reconfigurability among multiple invertible Boolean logic gates, achieving a peak accuracy of 95%. These results highlight the potential of the proposed p-bit as a promising building block for high-speed, low-power and universal Ising machines.