Momentum-resolved electronic excitations in the Mott insulatorSr2IrO4studied by resonant inelastic x-ray scattering

Abstract

We report an Ir L 3 edge resonant inelastic x-ray scattering measurement of the low-lying electronic excitations in Sr 2 IrO 4 over the complete Brillouin zone of the IrO 2 plane. A remarkably strong inelastic signal which exceeds the elastic scattering in intensity is observed. Peaks observed at 0.5, 3.2, and 6.0 eV are respectively ascribed to an interband transition across the Mott gap and charge-transfer excitations from the O 2p band to the Ir 5d bands. The dispersion of the Mott gap excitation is found to be particularly weak. This is interpreted as a signature of the narrow 5d bands of the novel Mott insulating state of Sr 2 IrO 4 induced by the strong spin-orbit interaction.

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

“…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].…”

“…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].…”

Noncollinear versus collinear description of the Ir-based one-t2g-hole perovskite-related compounds:SrIrO3andSr2Lado1, Pardo2 2015Phys. Rev. B12580View full textAdd to dashboardCite

“…6 These systems are also interesting because the role of spin-orbit coupling in the electronic structure is not completely clear, in particular it has been under debate what causes the insulating behavior in Sr 2 IrO 4 , whether the system is a Mott or a Slater insulator. [7][8][9][10][11][12] One of the keys to answer this question is to describe the electronic state the one t 2g hole is in. This has been described as a pure j ef f = 1/2 state 8, 13 or as a mixture due to contributions from both j ef f = 3/2 and e g states.…”

Pressure-Induced Confined Metal from the Mott InsulatorSr3Ir2O7Ding1, Yang2, Chen3 et al. 2016Phys. Rev. Lett.488820View full textAdd to dashboardCite

“…Previous RIXS studies [40][41][42][43] have identified peak D as a crystal-field excitation between the Ir 5d t 2g and e g orbitals, possibly mixed with a small amount (5%) of charge-transfer excitation from the oxygen 2p ligands [44]. In a nearly cubic crystal field, peak C is the spin-orbit exciton related to transition between the J eff =1/2 and 3/2 states [35,41,45].…”