RIXS studies of the low-energy magnetic excitations in double perovskite iridates La₂BIrO₆ (B=Co, Ni, Zn)

Ordered double perovskite (DP) materials [1-3], A₂BB'O₆, where B is a 3d and B' is a 4d or 5d transition metal ion, respectively, provide a rare opportunity to study the interaction between the intriguing magnetic behaviors of 5d systems and the better understood 3d magnetism, which is important for developing potential applications of these novel magnetic systems. Using resonant inelastic x-ray scattering (RIXS) measurements at Ir L₃ edge, we have investigated the low-energy magnetic excitations in a series of La₂BIrO₆ single crystals, where B is Co, Ni and Zn, respectively. In La₂CoIrO₆ and La₂NiIrO₆, clear magnetic excitations with a large magnon gap ~ 40 meV were revealed, indicating an extremely large magnetic anisotropy in the magnetic interaction in these two compounds containing magnetic 3d ions. In contrast, the low energy magnon mode was absent in La₂ZnIrO₆ in which the 3d ions are non-magnetic, suggesting the importance of 3d-5d hybridization in the magnetic properties of DP iridates.

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