Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba3ZnIr2O9

Nag, A, Middey, S, Bhowal, S, Panda, SK, Mathieu, R, Orain, JC, Bert, F, Mendels, P, Freeman, Paul Gregory orcid iconORCID: 0000-0002-5376-8940 et al (2016) Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba3ZnIr2O9. Physical Review Letters, 116 (9). 097205. ISSN 0031-9007

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Official URL: http://dx.doi.org/10.1103/PhysRevLett.116.097205


We show using detailed magnetic and thermodynamic studies and theoretical calculations that the ground state of Ba3ZnIr2O9 is a realization of a novel spin-orbital liquid state. Our results reveal that Ba3ZnIr2O9 with Ir5+ (5d(4)) ions and strong spin-orbit coupling (SOC) arrives very close to the elusive J = 0 state but each Ir ion still possesses a weak moment. Ab initio density functional calculations indicate that this moment is developed due to superexchange, mediated by a strong intradimer hopping mechanism. While the Ir spins within the structural Ir2O9 dimer are expected to form a spin-orbit singlet state (SOS) with no resultant moment, substantial frustration arising from interdimer exchange interactions induce quantum fluctuations in these possible SOS states favoring a spin-orbital liquid phase down to at least 100 mK.

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