Pressure-driven collapse of the relativistic electronic ground state in a honeycomb

J. Patrick Clancy, Hlynur Gretarsson, Jennifer A. Sears, Yogesh Singh, Serge Desgreniers, Kavita Mehlawat, Samar Layek, Gregory Kh Rozenberg, Yang Ding, Mary H. Upton, Diego Casa, Ning Chen, Junhyuck Im, Yongjae Lee, Ravi Yadav, Liviu Hozoi, Dmitri Efremov, Jeroen Van Den Brink, Young June Kim

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Abstract

Honeycomb-lattice quantum magnets with strong spin-orbit coupling are promising candidates for realizing a Kitaev quantum spin liquid. Although iridate materials such as Li2IrO3 and Na2IrO3 have been extensively investigated in this context, there is still considerable debate as to whether a localized relativistic wavefunction (J eff = 1/2) provides a suitable description for the electronic ground state of these materials. To address this question, we have studied the evolution of the structural and electronic properties of α-Li2IrO3 as a function of applied hydrostatic pressure using a combination of X-ray diffraction and X-ray spectroscopy techniques. We observe striking changes even under the application of only small hydrostatic pressure (P ≤ 0.1 GPa): A distortion of the Ir honeycomb lattice (via X-ray diffraction), a dramatic decrease in the strength of spin-orbit coupling effects (via X-ray absorption spectroscopy), and a significant increase in non-cubic crystal electric field splitting (via resonant inelastic X-ray scattering). Our data indicate that α-Li2IrO3 is best described by a J eff = 1/2 state at ambient pressure, but demonstrate that this state is extremely fragile and collapses under the influence of applied pressure.

Original languageEnglish
Article number35
Journalnpj Quantum Materials
Volume3
Issue number1
DOIs
Publication statusPublished - 2018 Dec 1

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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    Clancy, J. P., Gretarsson, H., Sears, J. A., Singh, Y., Desgreniers, S., Mehlawat, K., Layek, S., Rozenberg, G. K., Ding, Y., Upton, M. H., Casa, D., Chen, N., Im, J., Lee, Y., Yadav, R., Hozoi, L., Efremov, D., Van Den Brink, J., & Kim, Y. J. (2018). Pressure-driven collapse of the relativistic electronic ground state in a honeycomb. npj Quantum Materials, 3(1), [35]. https://doi.org/10.1038/s41535-018-0109-0