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The 27th AIRAPT International Conference on High Pressure Science and Technology
Abstract

Investigação


High pressure collapse of the Jeff=1/2 state in honeycomb Cu2IrO3 probed through x-ray spectroscopies

Authors:
Gilberto Fabbris (ANL - Argonne National Laboratory) ; Jungho Kim (ANL - Argonne National Laboratory) ; Mykola Abramchuk (BC - Boston College) ; Faranak Bahrami (BC - Boston College) ; Wenli Bi (ANL - Argonne National Laboratory, UIUC - University of Illinois at Urbana-Champaign) ; Jinkwarg Kim (ANL - Argonne National Laboratory) ; Christopher Dietl (ANL - Argonne National Laboratory) ; Mary Upton (ANL - Argonne National Laboratory) ; Omar Chmaissem (ANL - Argonne National Laboratory, NIU - Northern Illinois University) ; Timothy Elmslie (UF - University of Florida) ; James Hamlin (UF - University of Florida) ; Fazel Tafti (BC - Boston College) ; Daniel Haskel (ANL - Argonne National Laboratory)

Abstract:

Since the realization of the spin-orbit entangled Jeff states the properties of 4d and 5d oxides have been intensely scrutinized. Among the most exciting prospects of such Jeff states is the potential realization of a Kitaev quantum spin liquid in honeycomb lattices, as it is expected to host majorana fermions and the potential for topological quantum computing [1]. However, the realization of the Kitaev quantum spin liquid state has proven to be difficult because distortions of the honeycomb lattice tend to drive either magnetic order or dimerization. Cu2IrO3 has been recently synthesized [2], hosting a Jeff = 1/2 Ir (5d5) honeycomb lattice that appears to form a Kitaev quantum spin liquid [3,4]. Here we use pressure to understand the relationship between the structural/electronic motif and the magnetic state. This was achieved using a combination of x-ray diffraction and x-ray spectroscopies, namely x-ray absorption near edge structure, x-ray magnetic circular dichroism and resonant inelastic x-ray scattering. We find that high pressure dramatically modifies the underlying electronic structure of Cu2IrO3. Below about 15-20 GPa, pressure drives a suppression of the Jeff=1/2 state. The presence of a persistent XMCD signal and non-vanishing suggests that the Jeff state is replaced by spin-orbital locked pseudo-spins [5]. Beyond 20 GPa, a dramatic collapse of the c-axis occurs concomitantly with an electron transfer from Cu to Ir. This transition appears to fill the Ir t2g orbital (5d6), while leaving the Cu ions in an average configuration close to 3d9.5. The expected properties of such high-pressure phase will be discussed.

Work at Argonne is supported by the U.S. Department of Energy, Office of Science, under contract No. DE-AC-02-06CH11357.

1)    Nayak et al., Rev. Mod. Phys. 80, 1083 (2008)
2)    Abramchuk et al., J. Am. Chem. Soc. 139, 15371-15376 (2017)
3)    Kenney et al., arXiv:1811.00565 [cond-mat.str-el] (2018)
4)    Choi et al., Phys. Rev. Lett. 122, 167202 (2019)
5)    Bhattacharjee et al., New J. Phys. 14, 073015 (2012)