Magnetic interactions in the hidden altermagnet candidate MnS2

Pyrite MnS₂ is a collinear antiferromagnet (Tₙ ≈ 48 K) whose Mn²⁺ fcc sublattice and tilted MnS₆ octahedra create multiple symmetry-distinct superexchange pathways. Motivated by recent proposals of "hidden" altermagnetism in pyrite lattices, we investigate how geometrically inequivalent bonds lift degeneracies in the antiferromagnetic spin-wave spectrum. We combine time-of-flight inelastic neutron scattering on single-crystal MnS₂ with linear spin-wave modeling that resolves up to fifth-neighbor exchanges into environment-dependent subsets. Constant-Q/constant-E cuts map the full magnon dispersion emerging from the (1, ½, 0) ordering wave vector, with evidence of exchange asymmetry on the fifth-neighbor bonds. In addition, paramagnetic diffusive scattering at T = 55 K reveals incommensurate spin fluctuations that follow the underlying crystalline symmetry. Together, these results highlight the crucial role of bond-selective exchange in MnS₂ and establish pyrite magnets as fertile ground for exploring altermagnetic spin dynamics.