Engineering photomagnetism in collinear van der Waals antiferromagnets

TL;DR

This paper demonstrates that doping collinear van der Waals antiferromagnets with transition metal ions enhances photomagnetic responses, enabling efficient ultrafast optical control of spin dynamics for advanced spintronic applications.

Contribution

It introduces a novel doping strategy with TM ions to significantly boost d-d photomagnetism in van der Waals antiferromagnets, broadening control over spin precession.

Findings

Ni doping amplifies photomagnetic response by over tenfold.

Resonant optical pumping induces large coherent spin precession.

Effective across different magnetic states and tunable frequencies.

Abstract

Achieving efficient ultrafast optical control of antiferromagnetic spin dynamics is a central goal for next-generation high-speed THz spintronic and magnonic devices. Resonant optical pumping of crystal-field-split d-d orbital multiplets in magnetic TM ions directly modulates exchange and spin-orbit interactions, inducing large-amplitude coherent spin precession. However, such effects are limited to a handful of systems and there is no general strategy to enhance d-d photomagnetism in antiferromagnets. Here, we demonstrate the engineering of photomagnetism via TM-ion doping in collinear van der Waals antiferromagnets. In Mn$_{1-x}$Ni$_x$PS$_3$, small amounts of Ni$^{2+}$ activate a strong photomagnetic response while largely preserving the N\'eel ground state. Even 10% Ni boosts the response by more than an order of magnitude compared to pure MnPS$_3$, with resonant pumping of Ni$^{2+}$ d-d transitions driving large-amplitude coherent spin precession and providing helicity-dependent phase control. Tuning the pump energy across the full Mn$_{1-x}$Ni$_x$PS$_3$ composition range shows that Ni excitations remain effective across competing N\'eel and zig-zag antiferromagnetic states while supporting tunable-frequency coherent spin precession. These results establish TM-ion doping as a versatile strategy to harness orbital multiplet excitations for ultrafast, low-dissipation spin control in van der Waals antiferromagnets.