Light-Induced Néel Vector Reversal in 2D van der Waals Antiferromagnets

Abstract

Antiferromagnetic spintronics promises ultrafast device performance, yet the essential Néel vector reversal is hindered by its intrinsic immunity to external magnetic fields. Here, we propose a mechanism for deterministic Néel vector reversal in 2D van der Waals antiferromagnets enabled by ultrafast laser pulses. The core physics involves light-induced asymmetric interlayer demagnetization, which drives the antiferromagnet into a transient ferrimagnetic state with a finite net moment. This transient symmetry breaking allows the Néel vector to be controlled by an external magnetic field. We identify that the intrinsic structural and electronic asymmetries and spin–orbit-coupling mediated spin flips are essential for this process. Using first-principles calculations and real-time time-dependent density functional theory, we further demonstrate this mechanism in bilayer NiICl and YI2. Our work establishes a general strategy for the optical manipulation of 2D antiferromagnetic order.