Pressure tuning of bond-directional exchange interactions and magnetic frustration in the hyperhoneycomb iridate beta-Li2IrO3

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Veiga, L. S. I. ; Etter, M. ; Glazyrin, K. ; Sun, F. ; Escanhoela, C. A. Jr ; Fabbris, G. ; Mardegan, J. R. L. ; Malavi, P. S. ; Deng, Y. ; Stavropoulos, P. P. ; Kee, H. -Y. ; Yang, W. G. ; van Veenendaal, M. ; Schilling, J. ; Takayama, T. ; Takagi, H. ; Haskel, D.

• Tipo de documento: Artigo Científico
• Fonte: PHYSICAL REVIEW B; v. 96, n. 14, p. 6-pg., 2017-10-10.

Resumo

We explore the response of Ir 5d orbitals to pressure in beta-Li2IrO3, a hyperhoneycomb iridate in proximity to a Kitaev quantum spin-liquid (QSL) ground state. X-ray absorption spectroscopy reveals a reconstruction of the electronic ground state below 2 GPa, the same pressure range where x-ray magnetic circular dichroism shows an apparent collapse of magnetic order. The electronic reconstruction, which manifests a reduction in the effective spin-orbit interaction in 5d orbitals, pushes beta-Li2IrO3 further away from the pure Jeff = 1/2 limit. Although lattice symmetry is preserved across the electronic transition, x-ray diffraction shows a highly anisotropic compression of the hyperhoneycomb lattice which affects the balance of bond-directional Ir-Ir exchange interactions driven by spin-orbit coupling at Ir sites. An enhancement of symmetric anisotropic exchange over Kitaev and Heisenberg exchange interactions seen in theoretical calculations that use precisely this anisotropic Ir-Ir bond compression provides one possible route to the realization of a QSL state in this hyperhoneycomb iridate at high pressures. (AU)

• Processo FAPESP: 16/24137-3 - Estudo do magnetismo orbital em compostos de perovskita dupla sob condições extremas utilizando técnicas de radiação síncrotron
• Beneficiário: Carlos Augusto Escanhoela Júnior
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 13/14338-3 - Competição entre supercondutividade e magnetismo em sistemas sob pressão e filmes finos
• Beneficiário: Larissa Sayuri Ishibe Veiga
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado