Monte Carlo Study of an Unconventional Superconducting Phase in Iridium Oxide<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>J</mml:mi><mml:mi>eff</mml:mi></mml:msub><mml:mo mathvariant="bold">=</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:math>Mott Insulators Induced by Carrier Doping

Watanabe, Hiroshi; Shirakawa, Tomonori; Yunoki, Seiji

doi:10.1103/physrevlett.110.027002

Cited by 231 publications

(205 citation statements)

References 45 publications

(58 reference statements)

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“…Of the families of SOM states recently uncovered, layered quasi-two-dimensional Sr 2 IrO 4 (Sr-214) has received substantial attention 1 -partially due to theoretical predictions that this material may manifest an unconventional superconducting phase when doped 3,4 . In particular, model Hamiltonians of electron-doping in this Sr-214 compound have been mapped to those of hole-doping the Mott states of high temperature superconducting copper oxides, and empirical similarities between the 2D Heisenberg S = and Sr-214 6 have spurred further interest.…”

Section: Introductionmentioning

confidence: 99%

Influence of electron doping on the ground state of(Sr1−xLax)2IrO4

et al. 2015

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The evolution of the electronic properties of electron-doped (Sr1−xLax)2IrO4 is experimentally explored as the doping limit of La is approached. As electrons are introduced, the electronic ground state transitions from a spin-orbit Mott phase into an electronically phase separated state, where long-range magnetic order vanishes beyond x = 0.02 and charge transport remains percolative up to the limit of La substitution (x ≈ 0.06). In particular, the electronic ground state remains inhomogeneous even beyond the collapse of the parent state's long-range antiferromagnetic order, while persistent short-range magnetism survives up to the highest La-substitution levels. Furthermore, as electrons are doped into Sr2IrO4, we observe the appearance of a low temperature magnetic glass-like state intermediate to the complete suppression of antiferromagnetic order. Universalities and differences in the electron-doped phase diagrams of single layer and bilayer Ruddlesden-Popper strontium iridates are discussed.

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Section: Introductionmentioning

confidence: 99%

Influence of electron doping on the ground state of(Sr1−xLax)2IrO4

et al. 2015

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“…The theoretical understanding of the j = 1/2 AF insulator has been also reported [14,[18][19][20][21][22][23][24]. Moreover, even possible unconventional superconductivity has been proposed once mobile carriers are introduced into the insulating state [25][26][27][28]. However, the electronic structure in multi-orbital systems with the competition between the electron correlations and the SOC has not been thoroughly understood.…”

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Spin-orbit-induced exotic insulators in a three-orbital Hubbard model with(t2g)5electrons

2015

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On the basis of the multi-orbital dynamical mean field theory, a three-orbital Hubbard model with a relativistic spin-orbit coupling (SOC) is studied at five electrons per site. The numerical calculations are performed by employing the continuous-time quantum Monte Carlo (CTQMC) method based on the strong coupling expansion. We find that appropriately choosing bases, i.e., the maximally spin-orbit-entangled bases, drastically improve the sign problem in the CTQMC calculations, which enables us to treat exactly the full Hund's coupling and pair hopping terms. This improvement is also essential to reach at low temperatures for a large SOC region where the SOC most significantly affects the electronic structure. We show that a metal-insulator transition is induced by the SOC for fixed Coulomb interactions. The insulating state for smaller Coulomb interactions is antiferromagnetically ordered with the local effective total angular momentum j = 1/2, in which the j = 1/2 based band is essentially half-filled while the j = 3/2 based bands are completely occupied. More interestingly, for larger Coulomb interactions, we find that an excitonic insulating state emerges, where the condensation of an electron-hole pair in the j = 1/2 and j = 3/2 based bands occurs. The origin of the excitonic insulator as well as the experimental implication is discussed. In these materials, along with moderate electron correlations [6,7], there exists a strong relativistic spin-orbit coupling (SOC), which splits t 2g orbitals, already separated from e g orbitals due to a large crystal field, into the effective total angular momentum j = 1/2 doublet and j = 3/2 quartet orbitals in the atomic limit [8]. Since there are nominally five 5d electrons per Ir ion, the j = 1/2 orbital is half filled while the j = 3/2 orbitals are fully occupied.As opposed to simple expectation from strongly correlated 3d and 4d transition metal oxides [9][10][11][12][13], the experiments have revealed that the ground state of these Ir oxides is a j = 1/2 antiferromagnetic (AF) insulator [14][15][16][17]. The theoretical understanding of the j = 1/2 AF insulator has been also reported [14,[18][19][20][21][22][23][24]. Moreover, even possible unconventional superconductivity has been proposed once mobile carriers are introduced into the insulating state [25][26][27][28]. However, the electronic structure in multi-orbital systems with the competition between the electron correlations and the SOC has not been thoroughly understood. When the SOC is significantly large, the j = 1/2 based band is completely separated from the j = 3/2 based bands, and thus a single-orbital description of the j = 1/2 based band is expected to be valid. On the other hand, when the SOC is small, this picture breaks down and the electronic structure should be largely affected not only by Coulomb interactions but also by the multi-orbital nature. Therefore, a question naturally arises: what is the ground state of multi-orbital systems with the competition between the electron correlations and th...

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“…A strong spin-orbit coupling (SOC) causes t 2g orbitals split into effective total angular momenta j eff = 1/2 and 3/2. The relativistic electronic feature in these TM compounds has drawn much attraction recently as exotic electronic, magnetic, and topological phases have been expected, including J eff = 1/2 Mott insulator [1][2][3][4][5], superconductivity [6,7], topological insulator [8,9], Weyl semimetal [10,11], and spin liquid [12,13]. Among them, the research on t 5 2g systems forming a honeycomb lattice structure with edge-sharing ligands has been triggered by the possibility of a nontrivial topological phase [14,15] or a Kitaev-type spin liquid [16][17][18], attributed to their unique hopping geometry.…”

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From a Quasimolecular Band Insulator to a Relativistic Mott Insulator in t2g5 Systems with a Honeycomb Lattice Structure

2016

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The t2g orbitals of an edge-shared transition-metal oxide with a honeycomb lattice structure form dispersionless electronic bands when only hopping mediated by the edge-sharing oxygens is accessible. This is due to the formation of isolated quasimolecular orbitals (QMOs) in each hexagon, introduced recently by Mazin et al. [Phys. Rev. Lett. 109, 197201 (2012)], which stabilizes a band insulating phase for t 5 2g systems. However, with help of the exact diagonalization method to treat the electron kinetics and correlations on an equal footing, we find that the QMOs are fragile against not only the spin-orbit coupling (SOC) but also the Coulomb repulsion. We show that the electronic phase of t 5 2g systems can vary from a quasimolecular band insulator to a relativistic J eff = 1/2 Mott insulator with increasing the SOC as well as the Coulomb repulsion. The different electronic phases manifest themselves in electronic excitations observed in optical conductivity and resonant inelastic x-ray scattering. Based on our calculations, we assert that the currently known Ru 3+ -and Ir 4+ -based honeycomb systems are far from the quasimolecular band insulator but rather the relativistic Mott insulator. Introduction -Physical properties of 4d and 5d transition metal (TM) compounds with nominally less than six d electrons are determined by the t 2g manifold because of a strong cubic crystal field. A strong spin-orbit coupling (SOC) causes t 2g orbitals split into effective total angular momenta j eff = 1/2 and 3/2. The relativistic electronic feature in these TM compounds has drawn much attraction recently as exotic electronic, magnetic, and topological phases have been expected, including J eff = 1/2 Mott insulator [1-5], superconductivity [6,7], topological insulator [8,9], Weyl semimetal [10,11], and spin liquid [12,13]. Among them, the research on t 5 2g systems forming a honeycomb lattice structure with edge-sharing ligands has been triggered by the possibility of a nontrivial topological phase [14,15]

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Monte Carlo Study of an Unconventional Superconducting Phase in Iridium OxideJeff=1/2Mott Insulators Induced by Carrier Doping

Cited by 231 publications

References 45 publications

Influence of electron doping on the ground state of(Sr1−xLax)2IrO4

Influence of electron doping on the ground state of(Sr1−xLax)2IrO4

Spin-orbit-induced exotic insulators in a three-orbital Hubbard model with(t2g)5electrons

From a Quasimolecular Band Insulator to a Relativistic Mott Insulator in t2g5 Systems with a Honeycomb Lattice Structure

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