Magnetic structure and 5d-electronic state in a pyrochlore iridate Eu₂Ir₂O₇

The pyrochlore-type iridium oxide Eu2Ir2O7 exhibits a metal-insulator transition at 120 K, accompanied by magnetic ordering. We performed resonant x-ray scattering (RXS) experiment with photon energies near the iridium absorption edge L3 to investigate the arrangement of Ir4+ magnetic moments. Magnetic RXS was observed in the insulating phase, providing direct evidence of long-range ordering of Ir4+ magnetic moments with a propagation vector of (4n+2 0 0) . Our single-crystal structure analysis revealed that the lattice retains its face-centered-cubic structure across the metal-insulator transition, indicating all-in-all-out magnetic order, where all the magnetic moments on the four vertices of each Ir4+ tetrahedron point inward or outward as shown in Fig. 1 [1]. To investigate the 5d-electronic state of Ir4+, we performed resonant inelastic x-ray scattering (RIXS) experiment near the L3 edge. Obtained RIXS spectra indicate that the 5d-electronic state is affected by not only the spin-orbit interaction but also trigonal distortion of IrO6 octahedron [2].