Figure 1: All-in/all-out (AIAO) order and temperature dependences of magnetic susceptibility and resistivity.

(a) Crystal structure of Cd₂Os₂O₇. Cadmium, osmium and oxygen atoms in the cubic unit cell of 10.1618(8) Å in edge are shown by cyan, black and red spheres, respectively. Four Os atoms, each of which is octahedrally coordinated by six oxygen atoms, form a regular tetrahedron which shares vertices with the surrounding four tetrahedra, resulting in the three-dimensional network of the pyrochlore lattice. (b) AIAO magnetic order on the pyrochlore lattice made of osmium atoms. The arrows represent some osmium spins on the vertices of tetrahedra; the tetrahedra with the all-in and all-out configurations are colored in yellow-green and magenta, respectively. (c) Temperature dependences of M/H measured on a single crystal of Cd₂Os₂O₇. After cooling down to 2 K under zero magnetic field, magnetization was measured upon heating at a magnetic field of 2 T (ZFC) and then measured upon cooling at the same field (FC). The magnetic field was applied along the [110], [001], or [111] direction. (d) Temperature dependences of resistivity measured on a single crystal of Cd₂Os₂O₇. The measurements were done at zero magnetic field upon heating after cooling to 2 K in μ₀H_FC = 0 (ZFC) and 9 T (FC) along [111]. Electrical currents run along [10], perpendicular to the cooling field. Inset shows an expanded view of the low temperature region in the linear scale.