Ab initio study of the electronic properties and Fermi surface of the uranium dipnictides

The electronic structure of the uranium dipnictides $\mathrm{U}{X}_2$ ($X=\mathrm{As}$, Sb, and Bi) is investigated by means of ab initio calculations based on density functional theory. The calculated Fermi surfaces are presented and compared to available experimental models obtained from de Haas–van Alphen experiments. In agreement with experiments they are found to have a significant two-dimensional character. Also, the change of the electronic properties through the series is discussed.

Figure 1

(Color online) Left: the crystal structure of $\mathrm{U}{\mathrm{Bi}}_2$ showing the ↑↓ antiferromagnetic order. Right: the crystal structure of $\mathrm{U}{\mathrm{As}}_2$ and $\mathrm{U}{\mathrm{Sb}}_2$ showing the doubling of the magnetic cell with respect to the chemical cell and the ↑↓↓↑ antiferromagnetic sequence.

Figure 2

(Color online) Total (upper panel) and spin-polarized partial (lower panel) density of states for $\mathrm{U}{\mathrm{Bi}}_2$. The Fermi level is at zero energy and is marked with a vertical dashed line.

Figure 3

(Color online) Calculated band structure of $\mathrm{U}{\mathrm{Bi}}_2$. The Fermi level is at zero energy and is marked by a horizontal dashed line. The bands crossing the Fermi level are shown in red.

Figure 4

(Color online) Total (upper panel) and spin-polarized partial (lower panel) density of states for $\mathrm{U}{\mathrm{Sb}}_2$. The Fermi level is at zero energy and is marked with a vertical dashed line.

Figure 5

(Color online) Calculated band structure of $\mathrm{U}{\mathrm{Sb}}_2$. The Fermi level is at zero energy and is marked by a horizontal dashed line. The bands crossing the Fermi level are shown in red.

Figure 6

(Color online) Total (upper panel) and spin-polarized partial (lower panel) density of states for $\mathrm{U}{\mathrm{As}}_2$. The Fermi level is at zero energy and is marked with a vertical dashed line.

Figure 7

(Color online) Calculated band structure of antiferomagnetic $\mathrm{U}{\mathrm{As}}_2$. The Fermi level is at zero energy and is marked by a horizontal dashed line. The bands crossing the Fermi level are shown in red.

Figure 8

(Color online) Calculated (spin, orbital, total) and experimental (from Ref. 6) magnetic moment in ${\mu }_B$ per U atom for the $\mathrm{U}{X}_2$ series. The spin and orbital moments are represented by their absolute values. The total magnetic moment corresponds to ${\mu }_L-\mid {\mu }_S\mid$. The thin solid lines are a guide for the eyes.

Figure 9

(Color online) The Fermi surface of $\mathrm{U}{\mathrm{Bi}}_2$, shown in the first Brillouin zone centered around the $\Gamma$ point. The upper sheet is a hole surface, whereas the lower sheet is an electron surface.

Figure 10

(Color online) The Fermi surface of $\mathrm{U}{\mathrm{Sb}}_2$, centered around the $\Gamma$ point. The two upper sheets correspond to hole surfaces, whereas the two lower sheets are electron surfaces.

Figure 11

(Color online) The Fermi surface of $\mathrm{U}{\mathrm{As}}_2$, centered around the $\Gamma$ point. The two upper sheets correspond to hole surfaces, whereas the two lower sheets are electron surfaces.