Characterization and electronic structure calculations of the antiferromagnetic insulator ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$

We investigate the antiferromagnetic insulating nature of ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$ both experimentally and theoretically. Susceptibility measurements reveal a Néel temperature of $T_N\simeq 20\mathrm{K}$ and an effective magnetic moment of $5.3{\mu }_B∕\mathrm{fu}$. Mössbauer spectroscopy strongly suggests that the Fe ions, located at trigonal prismatic sites, are in a $3+$ high-spin state. Transport measurements display a simple Arrhenius law, with an activation energy of $\sim 0.2\mathrm{eV}$. The experimental results are interpreted with local spin-density approximation band-structure calculations, which confirm the ${\mathrm{Fe}}^{3+}$ state, the high-spin versus low-spin scenario, the antiferromagnetic ordering, and the value for the activation energy.

Figure 1

Susceptibility of ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$.

Figure 2

Temperature dependence of the resistivity of ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$, yielding an activation temperature $T_0=2200\mathrm{K}$.

Figure 3

(Color online) Partial densities of states (DOSs) of spin degenerate ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$.

Figure 4

(Color online) Partial $\mathrm{Fe}3d$ DOS of spin degenerate ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$.

Figure 5

(Color online) Partial $\mathrm{Rh}4d$ DOS of spin degenerate ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$.

Figure 6

(Color online) Partial DOS of antiferromagnetic ${\mathrm{Ca}}_3\mathrm{Fe}\mathrm{Rh}{\mathrm{O}}_6$.