arXiv subjects

Apoorva Chaturvedi

Publications and source records attributed to Apoorva Chaturvedi.

2 recordsLinked to original sources

arXiv2026

Deterministic control of antiferromagnetic domain walls by circular phonons

In an antiferromagnet, areas with different orientations of the antiferromagnetic Néel vector, which plays the role of the order parameter, can coexist, thus forming antiferromagnetic domains separated by domain walls. This suggests that antiferromagnets can possess the functionalities of magnetic storage media. Whether one can benefit from these functionalities crucially depends on the availability of efficient means for deterministic control of antiferromagnetic domain walls. Here, we demonstrate an approach to deterministically control domain walls in the van der Waals antiferromagnet Ni-doped $MnPS_3$ via dynamic engineering of the crystal lattice. By resonantly exciting a pair of nearly degenerate orthogonal infrared-active $A_u$ and $B_u$ phonon modes with circularly polarized mid-infrared light, we induce helicity-dependent reconfiguration of 180° antiferromagnetic domains, providing evidence for a phonon-induced effective field conjugate to the Néel order parameter. The domain kinetics exhibit a pronounced helicity asymmetry governed by the interplay between domain-wall elasticity and defect-mediated pinning, enabling small phonon-driven perturbations to accumulate into stable domain transformations. Our results establish dynamic lattice control and defect engineering as means for deterministic control of antiferromagnetic order.

cond-mat.mtrl-sci↗

arXiv2026

Engineering photomagnetism in collinear van der Waals antiferromagnets

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 Néel 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 Néel 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.

cond-mat.mtrl-sci↗