Figure 4 : Nickel under pressure.

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

Figure 4

(a) The t2g DOS of nickel at different values of the pressure. The van Hove peak and the sharp edge are smoothed with increasing pressure, but the Fermi level (EF=0) remains close to these two singular points. The cross at temperature T1 marks the beginning of the DOS steps, whereas the square at T2 marks is its ending. Their evolution with pressure is shown in the inset to b. (b) Non-interacting local spin susceptibility versus temperature at high pressures. The dashed lines are least-square fits of the high- and low-temperature region, which uncover the separation between the two Wilson-like behaviours, shifting towards higher temperatures compared to ambient pressure. The position of this kink (shown as hexagons in the inset) scales with the energy distance between EF and the sharp edge of the t2g DOS. (c) A consequence of the sharp features at the top of the band is the deviation of the quasiparticle scattering rate from the T2 law predicted by the Landau theory. Here this is shown for pure nickel, by plotting the scattering rates of one of the degenerate t2g and one of the degenerate eg orbitals, both at ambient pressure and at 330 GPa. The error bars come from averaging over different fit parameters (number of Matsubara frequencies and order of fit-polynomial).