Pressure-induced topological superconductivity in the spin–orbit Mott insulator GaTa4Se8

Park, Moon Jip; Sim, GiBaik; Jeong, Min Yong; Mishra, Archana; Han, Myung Joon; Lee, SungBin

doi:10.1038/s41535-020-0246-0

Cited by 21 publications

(13 citation statements)

References 64 publications

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“…The orbital component of the electron wavefunction can be decomposed into an s-wave-like (A 1 irrep of the point group T d of a tetrahedron) and three p-wavelike (T 2 irrep) wavefunctions. Spin-orbit coupling splits the electronic states of the isolated tetrahedron into two j = 1/2 doublets and a j = 3/2 quartet [22]. For the full pyrochlore lattice, this electronic structure persists close to the Γ point.…”

Section: J = 3/2 Fermions On the Pyrochlore Latticementioning

confidence: 97%

Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ fermions on the pyrochlore lattice

Kobayashi,

Bhattacharya,

Timm

et al. 2021

Preprint

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We examine the appearance of superconductivity in the strong-coupling limit of the Hubbard model on the pyrochlore lattice. We focus upon the limit of half filling, where the normal-state band structure realizes a j = 3/2 semimetal. Introducing doping, we show that the pairing is favored in a J = 2 quintet Eg state. The attractive interaction in this channel relies on the fact that Eg pairing on the pyrochlore lattice avoids the detrimental on-site repulsion. Our calculations show that a time-reversal symmetry-breaking superconducting phase is favored, which displays Bogoliubov Fermi surfaces.

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Section: J = 3/2 Fermions On the Pyrochlore Latticementioning

confidence: 97%

Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ fermions on the pyrochlore lattice

Kobayashi,

Bhattacharya,

Timm

et al. 2021

Preprint

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“…Novel physical phenomena have been observed in these compounds, e.g., the inelastic x-ray scattering analog of Young's double-slit experiment has been realized in Ba 3 CeIr 2 O 9 [9], where the molecular orbital formation within the Ir dimers is crucial. In lacunar spinels GaM 4 X 8 (M = Nb, Mo, Ta, and W and X = S, Se, and Te), spin-orbit coupled molecular J eff states [10,11] and topological superconductivity [12] have been proposed where molecular orbital formation within the tetrahedral cluster of M ions is the key.…”

Section: Introductionmentioning

confidence: 99%

Charge ordering in Ir dimers in the ground state of Ba5AlIr2O11

Katukuri

McNally

et al. 2022

Phys. Rev. B

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It has been well established experimentally that the interplay of electronic correlations and spin-orbit interactions in Ir 4+ and Ir 5+ oxides results in insulating J eff = 1/2 and J eff = 0 ground states, respectively. However, in compounds where the structural dimerization of iridium ions is favorable, the direct Ir d-d hybridization can be significant and takes a key role. Here, we investigate the effects of direct Ir d-d hybridization in comparison with electronic correlations and spin-orbit coupling in Ba 5 AlIr 2 O 11 , a compound with Ir dimers. Using a combination of ab initio many-body wave-function quantum chemistry calculations and resonant inelastic x-ray scattering experiments, we elucidate the electronic structure of Ba 5 AlIr 2 O 11 . We find excellent agreement between the calculated and the measured spin-orbit excitations. Contrary to expectations, the analysis of the many-body wave function shows that the two Ir (Ir 4+ and Ir 5+ ) ions in the Ir 2 O 9 dimer unit in this compound preserve their local J eff character close to 1/2 and 0, respectively. The local point group symmetry at each of the Ir ions plays an important role, significantly limiting the direct d-d hybridization. Our results emphasize that minute details in the local crystal field environment can lead to dramatic differences in the electronic states in iridates and 5d oxides in general.

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“…Cubic spinels with the chemical formula

A M_{2} X_{4}

are unarguably one of the largest compound families, comprising a plethora of transition metal ( M ) oxides and chalcogenides. [ 1–3 ] Lacunar spinels, being a populous subclass of spinels, have been attracting increasing attention because they offer a fertile ground for intriguing correlated and quantum states, such as a topological superconductor state, [ 4 ] spin‐orbit entangled molecular

J_{eff}

= 3/2 states, [ 5,6 ] Néel‐type skyrmions with polar dressing, [ 7 ] molecular cluster orbital‐driven ferroelectricity [ 7–12 ] and antiferroelectricity, [ 13 ] multiple multiferroic phases, [ 7,9,14,15 ] and magnetic states confined to polar domain walls. [ 14 ] Pressure‐induced superconductivity, [ 16 ] avalanche‐like breakdown of the Mott gap, leading to a resistive switching, [ 17 ] and colossal negative magnetoresistance [ 18,19 ] further witness the complexity of these compounds.…”

Section: Introductionmentioning

confidence: 99%

Optical, Dielectric, and Magnetoelectric Properties of Ferroelectric and Antiferroelectric Lacunar Spinels

Geirhos

Reschke

Ghara

et al. 2021

Physica Status Solidi (b)

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Lacunar spinels with a chemical formula of AM4X8 form a populous family of narrow‐gap semiconductors, which offer a fertile ground to explore correlation and quantum phenomena, including transition between Mott and spin‐orbit insulator states, ferro/antiferroelectricity driven by cluster Jahn‐Teller effect, and magnetoelectric response of magnetic skyrmions with polar dressing. The electronic and magnetic properties of lacunar spinels are determined to a large extent by their molecular‐crystal‐like structure. The interplay of electronic correlations with spin‐orbit and vibronic couplings leads to a complex electronic structure already on the single‐cluster level, which—together with weaker intercluster interactions—gives rise to a plethora of unconventional correlated states. This review primarily focuses on recent progresses in the field of optical, dielectric, and magnetoelectric properties on lacunar spinels. After introducing the main structural aspects, lattice dynamics and electronic structure of these compounds are discussed on the basis of optical spectroscopy measurements. Dielectric and polarization studies reveal the main characteristics of their low‐temperature ferro‐ or antiferroelectric phases as well as orbital fluctuations in their high‐temperature cubic state. Strong couplings between spin, lattice, and orbital degrees of freedom are manifested in singlet formation upon magnetostructural transitions, the emergence of various multiferroic phases, and exotic domain‐wall functionalities.

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Pressure-induced topological superconductivity in the spin–orbit Mott insulator GaTa4Se8

Cited by 21 publications

References 64 publications

Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ fermions on the pyrochlore lattice

Bogoliubov Fermi surfaces from pairing of emergent $j=3/2$ fermions on the pyrochlore lattice

Charge ordering in Ir dimers in the ground state of Ba5AlIr2O11

Optical, Dielectric, and Magnetoelectric Properties of Ferroelectric and Antiferroelectric Lacunar Spinels

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