Magnetic order and electronic structure of the $5d^3$ double perovskite ${\mathrm{Sr}}_2{\mathrm{ScOsO}}_6$

The magnetic susceptibility, crystal and magnetic structures, and electronic structure of the double perovskite ${\mathrm{Sr}}_2{\mathrm{ScOsO}}_6$ are reported. Using both neutron and x-ray powder diffraction we find that the crystal structure is monoclinic $P{2}_1/n$ from 3.5 to 300 K. Magnetization measurements indicate an antiferromagnetic transition at $T_{\mathrm{N}}=92\mathrm{K}$, one of the highest transition temperatures of any double perovskite hosting only one magnetic ion. Type I antiferromagnetic order is determined by neutron powder diffraction, with an Os moment of only $1.6\left(1\right){\mu }_{\mathrm{B}}$, close to half the spin-only value for a crystal field split $5d$ electron state with a $t_{2g}^3$ ground state. Density functional calculations show that this reduction is largely the result of strong Os-O hybridization, with spin-orbit coupling responsible for only a $\sim 0.1{\mu }_{\mathrm{B}}$ reduction in the moment.

Figure 1

Temperature dependence of the susceptibility measured in a 1 kOe applied field. Blue open symbols and red solid symbols show the zero-field-cooled (ZFC) and field-cooled (FC) (at 1 kOe) measurements, respectively. The inset shows the inverse susceptibility well above $T_{\mathrm{N}}$, and the result of a Curie-Weiss fit to the data (solid line).

Figure 2

Rietveld refinements against data (black crosses), collected at room temperature by NPD on POWGEN (main panel) and XRPD (inset). The difference between calculation and data is also shown, and is offset for clarity.

Figure 3

(a) NPD data collected with HB-2A at 115 K $\left(>T_{\mathrm{N}}\right)$, and 85 and 3.5 K $\left(<T_{\mathrm{N}}\right)$. Magnetic peaks are indicated by stars. (b) Results of Rietveld refinements of the 3.5 K data (solid line). (c) Intensity of scattering at $Q=0.78\AA$ against temperature (circles). The line is the result of a power-law fit against the data. The intensity is number of counts measured with the $Q=0.78\AA$ peak counted for 10 min per point. (d) The magnetic structure in one unit cell of ${\mathrm{Sr}}_2{\mathrm{ScOsO}}_6$, showing only Os and Sc ions. Moments are depicted along $a$, but their direction within the $a\text{−}b$ plane is unknown.

Figure 4

Calculated density of states and Os $d$ projections, from GGA+$U$ calculations including spin orbit. Os1 and Os2 denote the up and down spin Os relative to the global direction (set along the $a$ axis). The projections are per atom for a given spin, while the total is per spin for the two Os atom unit cell.