Figure 4.

Increasing anharmonicity of the lattice vibration and persisting magnetic excitations in AgCrSe₂ for T ≫ T_N, exemplified through the evolution with temperature of (a) constant Q = 4.1 Å⁻¹ cuts (symmetric in energy with respect to the elastic line) and (b) S(Q) integrated between 4 and 12 meV (as shown by the vertical arrow on Fig. 3b). All these cuts were extracted from the time-of-flight neutron data at λ_i = 2.2 Å, see the Experimental section for more details. The arrow on Fig. 4b illustrates the shift of the intensity maximum towards smaller Q as temperature increases, a sign of the decrease of the steepness of the dispersion.