Spin-orbit entangled j=1/2 moments in Ba2CeIrO6: A frustrated fcc quantum magnet

Spin-orbit entangled j=1/2 moments in Ba2CeIrO6 : A frustrated fcc quantum magnet

We establish the double perovskite Ba2CeIrO6 as a nearly ideal model system for j = 1/2 moments, with resonant inelastic x-ray scattering indicating that the ideal j = 1/2 state contributes by more than 99% to the ground-state wave function. The local j = 1/2 moments form an fcc lattice and are found to order antiferromagnetically at T-N = 14 K, more than an order of magnitude below the Curie-Weiss temperature. Model calculations show that the geometric frustration of the fcc Heisenberg antiferromagnet is further enhanced by a next-nearest neighbor exchange, and a significant size of the latter is indicated by ab initio theory. Our theoretical analysis shows that magnetic order is driven by a bond-directional Kitaev exchange and by local distortions via a strong magnetoelastic effect. Both, the suppression of frustration by Kitaev exchange and the strong magnetoelastic effect are typically not expected for j = 1/2 compounds making Ba2CeIrO6 a riveting example for the rich physics of spin-orbit entangled Mott insulators.

Loo, C. C. (author)
Kiese, D. (author)
Becker, P. (author)
Fröhlich, T. (author)
Lorenz, T. (author)
Sala, M. Moretti (author)
Monaco, G. (author)
Buessen, F. L. (author)
Attig, J. (author)
Hermanns, MariaStockholms universitet,Fysikum,Nordiska institutet för teoretisk fysik (Nordita)(Swepub:su)hermanns (author)
Streltsov, S. (author)
Khomskii, D. (author)
van den Brink, I. J. (author)
Braden, M. (author)
van Loosdrecht, P. H. M. (author)
Trebst, S. (author)
Paramekanti, A. (author)
Grüninger, M. (author)
Stockholms universitetFysikum (creator_code:org_t)

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