Figure 2 : Paramagnetic spin response of iron at ambient pressure.

From: Local magnetic moments in iron and nickel at ambient and Earth’s core conditions

Figure 2

(a) Temperature dependence of the local spin susceptibility in iron, calculated with DFT+DMFT. Calculations are performed following the non-ordered magnetic solution, also below the ferromagnetic transition temperature TC at which the uniform (Q=0) susceptibility diverges (not shown). in iron displays a marked 1/T Curie–Weiss behaviour, above as well as below TC, indicating the existence of robust local magnetic moments. The fits are least-square fits with fit function . For density–density, we obtain an effective local moment of and a Kondo temperature of TK=35 K, for Kanamori and TK=227 K. The DFT+DMFT data are compared to the uncorrelated and ‘bubble’ susceptibilities, that is, calculated, respectively, from the bare and ‘dressed’ Green’s functions, neglecting the effect of vertex corrections. Figure b shows the decay in imaginary time τ of the local spin susceptibility at two temperatures β=4 eV−1 (dashed lines) and β=30 eV−1 (full lines), for density–density (red) as well as Kanamori (blue). The fact that is going to zero much more slowly than β implies the presence of persistent local moments at these temperatures.