Figure 3.

Temperature dependence of bond distances between different sites of magnetic Mn atoms for NTE Mn₃Ge and PTE Mn₃Sn. (a) A layer of atoms in ab plane of $4\times 4\times 1$ supercell for Mn₃A (A = Ge and Sn), ${\text{d}}_1$ and ${\text{d}}_2$ mean the bond distances of Mn–Mn (I) and Mn–Mn (II) in the ab plane, respectively. Temperature dependence of ${\text{d}}_1$ and ${\text{d}}_2$ for (b) Mn₃Ge, and (c) Mn₃Sn. (d) Temperature dependence of relative change of $\left(\text{Δ}{\text{d}}_1+\text{Δ}{\text{d}}_2\right)$ Δd₁+Δd₂ for Mn₃A (A = Ge and Sn).