Unidirectional spin density wave state in metallic (Sr1−xLa
                x
              )2IrO4

Chen, X.; Schmehr, Julian; Islam, Zahirul; Porter, Zach; Zoghlin, Eli; Finkelstein, K. D.; Ruff, Jacob P. C.; Wilson, Stephen D.

doi:10.1038/s41467-017-02647-1

Cited by 38 publications

(41 citation statements)

References 38 publications

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“…For the same doping a SCM appears at 60 meV. Since the spectral weight in these modes is far too high for phonons, they have to correspond to electronic (5), and E u (6) modes (see Table II), each overlapping with the energy of the SCM. Fano-type asymmetry has also been observed for the Raman active phonons in the doped material [12].…”

Section: Methods and Resultsmentioning

confidence: 99%

“…It has been suggested that this material can be turned into a high T c superconductor [2]. While antiferromagnetism and spin density wave order have been reported for different doping concentrations [3][4][5], up to date transport and magnetization data have not revealed superconductivity [3,6]. A recent angle resolved photoemission (ARPES) study found an anisotropic pseudogap in Sr 2−y La y IrO 4 [6].…”

Section: Introductionmentioning

confidence: 99%

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Mott transition and collective charge pinning in electron doped Sr2IrO4

et al. 2018

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We studied the in-plane dynamic and static charge conductivity of electron doped Sr 2 IrO 4 using optical spectroscopy and DC transport measurements. The optical conductivity indicates that the pristine material is an indirect semiconductor with a direct Mott gap of 0.55 eV. Upon substitution of 2% La per formula unit the Mott gap is suppressed except in a small fraction of the material (15%) where the gap survives, and overall the material remains insulating. Instead of a zero energy mode (or Drude peak) we observe a soft collective mode (SCM) with a broad maximum at 40 meV. Doping to 10% increases the strength of the SCM, and a zero-energy mode occurs together with metallic DC conductivity. Further increase of the La substitution doesn't change the spectral weight integral up to 3 eV. It does however result in a transfer of the SCM spectral weight to the zero-energy mode, with a corresponding reduction of the DC resistivity for all temperatures from 4 to 300 K. The presence of a zero-energy mode signals that at least part of the Fermi surface remains ungapped at low temperatures, whereas the SCM appears to be caused by pinning a collective frozen state involving part of the doped electrons.

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Section: Methods and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mott transition and collective charge pinning in electron doped Sr2IrO4

et al. 2018

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“…In perovskite manganites, the parent antiferromagnetic (AFM) order develops into a ferromagnetic (FM) phase hosting giant magnetoresistance [2]. On the other hand, in both S = 1/2 cuprates [1] and J eff = 1/2 iridates [3][4][5][6], doping suppresses long-range AFM order leading to the formation of incommensurate spin-density wave order [7][8][9][10] with a conventional paramagnetic (PM) metal eventually emerging.…”

Section: Introductionmentioning

confidence: 99%

Persistence of antiferromagnetic order upon La substitution in the 4d4 Mott insulator Ca2RuO4

et al. 2018

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The chemical and magnetic structures of the series of compounds Ca 2−x La x RuO 4 [x = 0, 0.05(1), 0.07(1), 0.12(1)] have been investigated using neutron diffraction and resonant elastic x-ray scattering. Upon La doping, the low-temperature S-P bca space group of the parent compound is retained in all insulating samples [x 0.07(1)], but with significant changes to the atomic positions within the unit cell. These changes can be characterized in terms of the local RuO 6 octahedral coordination: with increasing doping, the structure, crudely speaking, evolves from an orthorhombic unit cell with compressed octahedra to a quasitetragonal unit cell with elongated ones. The magnetic structure on the other hand, is found to be robust, with the basic k = (0,0,0), b-axis antiferromagnetic order of the parent compound preserved below the critical La doping concentration of x ≈ 0.11. The only effects of La doping on the magnetic structure are to suppress the A-centred mode, favoring the B mode instead, and to reduce the Néel temperature somewhat. Our results are discussed with reference to previous experimental reports on the effects of cation substitution on the d 4 Mott insulator Ca 2 RuO 4 , as well as with regard to theoretical studies on the evolution of its electronic and magnetic structure. In particular, our results rule out the presence of a proposed ferromagnetic phase, and suggest that the structural effects associated with La substitution play an important role in the physics of the system.

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“…Interestingly, Sr-214 doped by electrons is thought to be a nearly perfect analogue to hole-doped cuprates (4,15). It exhibits many of the same electronic phenomena emerging with doping, such as a pseudogap (12,15,(26)(27)(28), Fermi arcs (29) and an incommensurate spin density wave (30). Although superconductivity is yet to be achieved, it has been theoretically predicted to occur at higher electron densities (31), if those were to be experimentally achieved.…”

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Atomic-scale fragmentation and collapse of antiferromagnetic order in a doped Mott insulator

et al. 2019

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Disentangling the relationship between the insulating state with a charge gap and the magnetic order in an antiferromagnetic (AF) Mott insulator remains difficult due to inherent phase separation as the Mott state is perturbed. Measuring magnetic and electronic properties at the atomic length scales would provide crucial insight, but this is yet to be experimentally achieved. Here we use spectroscopic-imaging spin-polarized scanning tunneling microscopy (SP-STM) to visualize periodic spin-resolved modulations originating from the AF order in a relativistic Mott insulator Sr2IrO4, and study these as a function of doping. We find that near insulator-to-metal transition (IMT), the long-range AF order melts into a fragmented state with short-range AF correlations. Crucially, we discover that the short-range AF order is locally uncorrelated with the observed spectral gap magnitude. This strongly suggests that short range AF correlations are unlikely to be the culprit behind inhomogeneous gap closing and the emergence of pseudogap regions near IMT. Our work establishes SP-STM as a powerful tool for revealing atomic-scale magnetic information in complex oxides.A Mott insulator, characterized by localization of electrons due to strong electron-electron interactions (1), is typically accompanied by magnetic ordering (2-4). The antiferromagnetic (AF)

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Unidirectional spin density wave state in metallic (Sr1−xLa x )2IrO4

Cited by 38 publications

References 38 publications

Mott transition and collective charge pinning in electron doped Sr2IrO4

Mott transition and collective charge pinning in electron doped Sr2IrO4

Persistence of antiferromagnetic order upon La substitution in the 4d4 Mott insulator Ca2RuO4

Atomic-scale fragmentation and collapse of antiferromagnetic order in a doped Mott insulator

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