Complex pressure-temperature structural phase diagram of the honeycomb iridate 
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Fabbris, G.; Thorn, Aidan; Bi, Wenli; Abramchuk, Mykola; Bahrami, Faranak; Kim, J. H.; Shinmei, Toru; Irifune, Tetsuo; Tafti, Fazel; Kolmogorov, Aleksey N.; Haskel, D.

doi:10.1103/physrevb.104.014102

Cited by 18 publications

(30 citation statements)

References 53 publications

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“…Our DFT calculations capture a pressure dependent structural transition at ∼7 GPa, but from P 2 1 /c to P 1 structure, which involves dimerization of Ir-Ir bonds in 2D honeycomb layers of Cu 2 IrO 3 . We show that presence of mixed valence disorder in Ir-Cu honeycomb layers are responsible for theoretically predicted [40] metallicity in Cu 2 IrO 3 at ambient pressure. At ambient pressure, Cu 2 IrO 3 is an insulator having an energy band gap of 0.3 eV (as extracted from the high T Arrhenius fit of our resistivity data), which has been simulated by substituting Cu in honeycomb layers with Li atoms.…”

Section: Introductionmentioning

confidence: 73%

“…Interestingly, high-pressure resistivity measurements on this system [41] have shown that the second structural transition is associated with an insulator to metal transition. However, DFT calculations [40] could not capture the same and predicted opening up of a gap of ∼0.3 eV in the dimerized phase.…”

Section: Introductionmentioning

confidence: 94%

“…More recently, optical phonons renormalization below the Kitaev temperature scale of ∼120 K has been quantitatively attributed to the interaction of phonons with the Majorana fermions [37]. Recent high-pressure studies on the Cu 2 IrO 3 system [40,41] have detected two pressure-induced structural transitions at ∼7 GPa and 11-15 GPa. While the first transition is reported to be to a triclinic α − P 1 followed by Ir-Ir dimerization, the high-pressure structure after the second transition was only predicted by DFT based evolutionary structure search method and could not be uniquely determined by a successful refinement of the PXRD pattern.…”

Section: Introductionmentioning

confidence: 99%

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Pressure tuning of structure, magnetic frustration and carrier conduction in Kitaev spin liquid candidate Cu$_2$IrO$_3$: X-ray, Raman, magnetic susceptibility, resistivity and first-principles analysis

Pal¹,

Malavi²,

Sinha³

et al. 2022

Preprint

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The layered honeycomb lattice iridate Cu 2 IrO 3 is the closest realization of the Kitaev quantum spin liquid, primarily due to the enhanced interlayer separation and nearly ideal honeycomb lattice.We report pressure-induced structural evolution of Cu 2 IrO 3 by powder x-ray diffraction (PXRD) up to ∼17 GPa and Raman scattering measurements up to ∼25 GPa. A structural phase transition (monoclinic C2/c → triclinic P 1) is observed with a broad mixed phase pressure range (∼4 to 15 GPa). The triclinic phase consists of heavily distorted honeycomb lattice with Ir-Ir dimer formation and a collapsed interlayer separation. In the stability range of the low-pressure monoclinic phase, structural evolution maintains the Kitaev configuration up to 4 GPa. This is supported by the observed enhanced magnetic frustration in dc susceptibility without emergence of any magnetic ordering and an enhanced dynamic Raman susceptibility. High-pressure resistance measurements up to 25 GPa in the temperature range 1.4-300 K show resilient non-metallic R(T ) behaviour with significantly reduced resistivity in the high-pressure phase. The Mott 3D variable-range-hopping conduction with much reduced characteristic energy scale T 0 suggests that the high-pressure phase is at the boundary of localized-itinerant crossover. Using first-principles density functional theoretical (DFT) calculations, we find that at ambient pressure Cu 2 IrO 3 exists in monoclinic P 2 1 /c phase which is energetically lower than C2/c phase (both the structures are consistent with experimental XRD pattern). DFT reveals structural transition from P 2 1 /c to P 1 structure at 7 GPa (involving dimerization of Ir-Ir bonds) in agreement with experimentally observed transition pressure.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Pressure tuning of structure, magnetic frustration and carrier conduction in Kitaev spin liquid candidate Cu$_2$IrO$_3$: X-ray, Raman, magnetic susceptibility, resistivity and first-principles analysis

Pal¹,

Malavi²,

Sinha³

et al. 2022

Preprint

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“…Examination of DOS profiles near the Fermi level can indeed provide insights into materials' various properties ranging from transport, superconductivity, and mag- netism to stability. The presence of a pseudo-gap and the population of bonding states has been found to correlate with structure's favorability in numerous cases [5,76,105]. For instance, our studies of related chemical systems have shown that the unusual stoichiometry of LiB x (x ∼ 0.9) and the stability of NaSn 2 result from the placement of the Fermi level near the bottom of a well-defined DOS valley [5,76,106].…”

Section: Analysis Of Electronic and Other Properties Of Ambient-press...mentioning

confidence: 94%

Prediction of stable Li-Sn compounds: boosting ab initio searches with neural network potentials

Kharabadze,

Thorn,

Koulakova

et al. 2022

Preprint

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The Li-Sn binary system has been the focus of extensive research because it features Li-rich alloys with potential applications as battery anodes. Our present re-examination of the binary system with a combination of machine learning and ab initio methods has allowed us to screen a vast configuration space and uncover a number of overlooked thermodynamically stable alloys. At ambient pressure, our evolutionary searches identified a new stable Li3Sn phase with a large BCCbased hR48 structure and a possible high-T LiSn4 ground state. By building a simple model for the observed and predicted Li-Sn BCC alloys we constructed an even larger viable hR75 structure at an exotic 19:6 stoichiometry. At 20 GPa, new 11:2, 5:1, and 9:2 phases found with our global searches destabilize previously proposed phases with high Li content. The findings showcase the appreciable promise machine learning interatomic potentials hold for accelerating ab initio prediction of complex materials.

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“…Therefore, pressureinduced dimerization should be expected even in honeycomb iridates like Ag 3 LiIr 2 O 6 and H 3 LiIr 2 O 6 that are strongly affected by structural randomness. Indeed, re-cent pressure work on Cu 2 IrO 3 revealed the formation of Ir-Ir dimers despite abundant stacking faults in that compound [47].…”

Section: Magnetismmentioning

confidence: 99%

Pressure-induced dimerization and collapse of antiferromagnetism in the Kitaev material $α$-Li$_2$IrO$_3$

Shen,

Breitner,

Prishchenko

et al. 2021

Preprint

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We present magnetization measurements carried out on polycrystalline and single-crystalline samples of α-Li2IrO3 under hydrostatic pressures up to 2 GPa and establish the temperature-pressure phase diagram of this material. The Néel temperature (TN) of α-Li2IrO3 is slightly enhanced upon compression with dTN/dp = 1.5 K/GPa. Above 1.2 GPa, α-Li2IrO3 undergoes a first-order phase transition toward a nonmagnetic dimerized phase, with no traces of the magnetic phase observed above 1.8 GPa at low temperatures. The critical pressure of the structural dimerization is strongly temperature-dependent. This temperature dependence is well reproduced on the ab initio level by taking into account lower phonon entropy in the nonmagnetic phase. We further show that the initial increase in TN of the magnetic phase is due to a weakening of the Kitaev interaction K along with the enhancement of the Heisenberg term J and off-diagonal anisotropy Γ. Our study reveals a common thread in the interplay of magnetism and dimerization in pressured Kitaev materials.

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Complex pressure-temperature structural phase diagram of the honeycomb iridate Cu2IrO3

Cited by 18 publications

References 53 publications

Pressure tuning of structure, magnetic frustration and carrier conduction in Kitaev spin liquid candidate Cu$_2$IrO$_3$: X-ray, Raman, magnetic susceptibility, resistivity and first-principles analysis

Pressure tuning of structure, magnetic frustration and carrier conduction in Kitaev spin liquid candidate Cu$_2$IrO$_3$: X-ray, Raman, magnetic susceptibility, resistivity and first-principles analysis

Prediction of stable Li-Sn compounds: boosting ab initio searches with neural network potentials

Pressure-induced dimerization and collapse of antiferromagnetism in the Kitaev material $α$-Li$_2$IrO$_3$

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