Optical and transport properties of the magnetic semiconductor α‐RuCl<sub>3</sub>

Binotto, L.; Pollini, I.; Spinolo, G.

doi:10.1002/pssb.2220440126

Cited by 60 publications

(69 citation statements)

References 15 publications

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“…However, in RuCl 3 delocalized, intersite charge excitations are located at significantly higher energies (above 0.9 eV), as described in the latter part of our manuscript. Further evidence for this point is provided by photoconductivity measurements, which show a strong onset (indicating delocalized states) near 1 eV [22]. We therefore believe that A 0 and the sharp RIXS feature do not share a common origin and that A 0 instead cor- responds to the onsite SO exciton.…”

Section: +mentioning

confidence: 84%

Spin-orbit excitations and electronic structure of the putative Kitaev magnetα−RuCl3

Sandilands¹,

Tian²,

Reijnders³

et al. 2016

Phys. Rev. B

186

161

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Mott insulators with strong spin-orbit coupling have been proposed to host unconventional magnetic states, including the Kitaev quantum spin liquid. The 4d system α-RuCl3 has recently come into view as a candidate Kitaev system, with evidence for unusual spin excitations in magnetic scattering experiments. We apply a combination of optical spectroscopy and Raman scattering to study the electronic structure of this material. Our measurements reveal a series of orbital excitations involving localized total angular momentum states of the Ru ion, implying that strong spin-orbit coupling and electron-electron interactions coexist in this material. Analysis of these features allows us to estimate the spin-orbit coupling strength as well as other parameters describing the local electronic structure, revealing a well-defined hierarchy of energy scales within the Ru d states. By comparing our experimental results with density functional theory calculations, we also clarify the overall features of the optical response. Our results demonstrate that α-RuCl3 is an ideal material system to study spin-orbit coupled magnetism on the honeycomb lattice.Introduction.-A variety of novel electronic phases are predicted to emerge in the solid state due to the cooperative action of spin-orbit coupling and electron correlation [1]. One prominent example is the proposed realization of the Heisenberg-Kitaev model in a strongly spin-orbit coupled Mott insulator on the honeycomb lattice [2,3]. In this scenario, the combination of spin-orbit coupling and orbital degeneracy leads to the formation of j ef f = 1/2 pseudospins. The spatial anisotropy inherent to these pseudospins in turn yields bond-dependent, anisotropic exchange interactions that can be mapped onto a generalized Heisenberg-Kitaev model [4], which hosts a variety of unusual magnetic states, including the Kitaev quantum spin liquid [5]. Experimental work in this direction has focussed on honeycomb lattice iridates [6,7], although the electronic structure of these materials is complicated by structural distortions and electron itinerancy [8].

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Section: +mentioning

confidence: 84%

Spin-orbit excitations and electronic structure of the putative Kitaev magnetα−RuCl3

Sandilands¹,

Tian²,

Reijnders³

et al. 2016

Phys. Rev. B

186

161

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“…RuCl 3 has been known for a long time and is even of some importance as a chemical [10]. Its electronic structure has been repeatedly investigated over the years by optical spectroscopy and photoemission [11][12][13]. The picture of a Mott-insulating state was proposed where the Ru 4d bands are situated close to E F but show little dispersion [13].…”

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confidence: 99%

JeffDescription of the Honeycomb Mott Insulatorα−RuCl3

Koitzsch¹,

Habenicht²,

Muller³

et al. 2016

Phys. Rev. Lett.

108

107

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Novel ground states might be realized in honeycomb lattices with strong spin-orbit coupling. Here we study the electronic structure of α-RuCl3, in which the Ru ions are in a d 5 configuration and form a honeycomb lattice, by angle-resolved photoemission, x-ray photoemission and electron energy loss spectroscopy supported by density functional theory and multiplet calculations. We find that α-RuCl3 is a Mott insulator with significant spin-orbit coupling, whose low energy electronic structure is naturally mapped onto J ef f states. This makes α-RuCl3 a promising candidate for the realization of Kitaev physics. Relevant electronic parameters such as the Hubbard energy U, the crystal field splitting 10Dq and the charge transfer energy ∆ are evaluated. Furthermore, we observe significant Cl photodesorption with time, which must be taken into account when interpreting photoemission and other surface sensitive experiments.

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“…Initially labeled as a semiconductor with a small gap of 0.3 eV [16], it was later discussed as a Mott-insulator [17] in which spin-orbit coupling plays a critical role [18]. A number of experimental studies with very different techniques have revealed a rich and intriguing paradigm of magnetism in this system [19-23, 25, 26].…”

mentioning

confidence: 99%