Controlling Magnetism in the 2D van der Waals Antiferromagnet CrPS₄ via Ion Intercalation

Two-dimensional (2D) van der Waals (vdW) magnetic materials are platforms in which inserting chemical species into their interlayer gaps offers a powerful route to engineer magnetism. Here, we focus on the A-type antiferromagnetic semiconductor CrPS₄ (T_N = 38 K) and investigate its electronic and magnetic properties upon intercalation of lithium (Li⁺) and organic tetrabutylammonium (TBA⁺) ions using first-principles calculations. Li⁺ incorporation induces a semiconductor-to-metal transition in CrPS₄ and triggers a switching from an out-of-plane antiferromagnetism state to an in-plane ferromagnetic state. This is accompanied by an increase of the ordering temperature, reaching a 5-fold enhancement for Li_0.5CrPS₄. TBA⁺ intercalation expands the vdW gap, decoupling CrPS₄ layers and stabilizing in-plane ferromagnetism with T_C > 100 K. Furthermore, it enhances magnon group velocities and yields more isotropic magnon transport. This work highlights intercalation as a powerful approach for tailoring magnetism, paving the way for tunable 2D-layered magnetic materials for spintronic and magnonic applications.