Model analysis of magnetic susceptibility of 
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: A two-dimensional 
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Takayama, T.; Matsumoto, Akiyo; Jackeli, George; Takagi, H.

doi:10.1103/physrevb.94.224420

Cited by 25 publications

(23 citation statements)

References 37 publications

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“…The pseudospin-lattice coupling is, for example, manifested as anomalous broadening of the linewidth of some Raman-active phonon modes [84,85] and hardening of optical phonons across T N [42]. The rotational behavior of pseudospins under external magnetic fields, reported in magnetometry [69], torque magnetometry [86], and magnetoresistance [87] studies, is consistent with the presence of pseudospin-lattice coupling. Further, the most recent detailed analysis shows that the behavior is incompatible with four-fold symmetric anisotropy expected for tetragonal symmetry and instead is well described by a pseudospin-lattice coupling [79,82].…”

Section: Overview Of Experimental Resultsmentioning

confidence: 57%

“…Figures are adopted from Ref [20]. patterns along the c-axis is governed by small energy scale interlayer couplings[69], the complete magnetic structure vitally defines the space and point group symmetries, with consequences to selection rules in optical transitions. This is relevant to the optical second harmonic generation experiment discussed in Section 4.b.…”

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confidence: 99%

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Square Lattice Iridates

Bertinshaw

Kim

Khaliullin

et al. 2019

Annu. Rev. Condens. Matter Phys.

100

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Over the last few years, Sr 2 IrO 4 , a single-layer member of the Ruddlesden-Popper series iridates, has received much attention as a close analog of cuprate high-temperature superconductors.Although there is not yet firm evidence for superconductivity, a remarkable range of cuprate phenomenology has been reproduced in electron-and hole-doped iridates including pseudogaps, Fermi arcs, and d-wave gaps. Further, a number of symmetry breaking orders reminiscent of those decorating the cuprate phase diagram have been reported using various experimental probes. We discuss how the electronic structures of Sr 2 IrO 4 through strong spin-orbit coupling leads to the low-energy physics that had long been unique to cuprates, what the similarities and differences between cuprates and iridates are, and how these advance the field of high-temperature superconductivity by isolating essential ingredients of superconductivity from a rich array of phenomena that surround it. Finally, we comment on the prospect of finding a new high-temperature superconductor based on the iridate series. b c a Sr O Ir a b c pseudospin-1/2 J a b FIG. 1. Crystal and magnetic structures of Sr 2 IrO 4 . (a) The crystal structure is based on Ref. [26] according to which the space group is I4 1 /acd. However, recent studies indicate that the symmetry is lower and most probably is I4 1 /a [27-29]. (b) Quasi-2D network of Ir and O. (c) The magnetic structure from Ref. [2]. II. MAPPING ONTO CUPRATE PHYSICSSoon after the discovery of HTSC in the cuprates, many complex oxides with a K 2 NiF 4 structure (isostructural to La 2 CuO 4 ) and its variants were searched for signs of superconductivity. Among these were Sr 2 RhO 4 and Sr 2 IrO 4 [30], which are "one-hole" systems, albeit with a t 2g -hole in the low-spin d 5 configuration as opposed to an e g -hole in cuprates. However, it was quickly apparent that 4d and 5d systems tend to be rather weakly correlated. In fact, Sr 2 RhO 4 is a Fermi liquid metal [31, 32] with a Fermi surface understood qualitatively in terms of a band structure calculated using density functional theory within the local density approximation (LDA) [33, 34]. Interestingly, the Fermi surfaces of Sr 2 RhO 4 and Sr 2 IrO 4 , calculated without SOC, are near indistinguishable due to their almost identical crystal structures with less than 1% difference in their lattice parameters [30]. A closer inspection, however, reveals that LDA does not accurately replicate the measured FermiX M X E-μ (eV) E-μ (eV) E-μ (eV) M X Γ Γ Γ Γ Γ Γ U ζ ζ μ wide band metal narrow J eff =1/2 band J eff =1/2 Mott state LDA+SOC LDA LDA+SOC+U t 2g band J eff =1/2 band J eff =3/2 band J eff =3/2 band J eff =1/2 UHB J eff =1/2 LHB FIG. 2. Illustration of the SOC driven Mott transition. Introduction of SOC splits off a narrow band near the Fermi level (orange solid lines), for which a moderate Coulomb interaction U ∼2 eV is sufficient to open a gap.observation of a significant gap reduction across T N , a typical Slater behavior, supports this viewpoint [42,43]. On th...

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Section: Overview Of Experimental Resultsmentioning

confidence: 57%

mentioning

confidence: 99%

Square Lattice Iridates

Bertinshaw

Kim

Khaliullin

et al. 2019

Annu. Rev. Condens. Matter Phys.

100

View full text Add to dashboard Cite

show abstract

“…1(b). The nearest layer term J 1c is partially frustrated due to the staggering of pseudospins in adjacent layers as has been pointed out in an earlier study [35]. The next nearest layer term J 2c is responsible for the uudd or uddu stacking patterns ( Fig.…”

Section: Mechanisms For In-plane Anisotropymentioning

confidence: 53%

“…For the measurements along [1 1 0] shown in red, a decrease in the magnetization is observed at low temperature, which points to a temperature dependent anisotropy. We note that it requires a very high quality sample to observe the in-plane anisotropy as it was not visible in previous magnetization measurements [35] [see Supplementary Materials (SM) for a description of our samples].…”

Section: B In-plane Magnetic Anisotropymentioning

confidence: 99%

Pseudospin-lattice coupling in the spin-orbit Mott insulator Sr2IrO4

et al. 2019

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Spin-orbit entangled magnetic dipoles, often referred to as pseudospins, provide a new avenue to explore novel magnetism inconceivable in the weak spin-orbit coupling limit, but the nature of their low-energy interactions remains to be understood. We present a comprehensive study of the static magnetism and low-energy pseudospin dynamics in the archetypal spin-orbit Mott insulator Sr2IrO4. We find that in order to understand even basic magnetization measurements, a formerly overlooked in-plane anisotropy is fundamental. In addition to magnetometry, we use neutron diffraction, inelastic neutron scattering and resonant elastic and inelastic x-ray scattering to identify and quantify the interactions that determine the global symmetry of the system and govern the linear responses of pseudospins to external magnetic fields and their low-energy dynamics. We find that a pseudospin-only Hamiltonian is insufficient for an accurate description of the magnetism in Sr2IrO4 and that pseudospin-lattice coupling is essential. This finding should be generally applicable to other pseudospin systems with sizable orbital moments sensitive to anisotropic crystalline environments.

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“…It has been established that the dominant term in the magnetic Hamiltonian in Sr 2 IrO 4 and Ba 2 IrO 4 is an isotropic 2D Heisenberg coupling between J eff = 1/2 moments [4,5,44].…”

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confidence: 99%

Two-Dimensional Jeff=1/2 Antiferromagnetic Insulator Unraveled from Interlayer Exchange Coupling in Artificial Perovskite Iridate Superlattices

et al. 2017

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We report an experimental investigation of the two-dimensional J eff = 1/2 antiferromagnetic Mott insulator by varying the interlayer exchange coupling in [(SrIrO3)1, (SrTiO3)m] (m = 1, 2 and 3) superlattices. Although all samples exhibited an insulating ground state with long-range magnetic order, temperature-dependent resistivity measurements showed a stronger insulating behavior in the m = 2 and m = 3 samples than the m = 1 sample which displayed a clear kink at the magnetic transition. This difference indicates that the blocking effect of the excessive SrTiO3 layer enhances the effective electron-electron correlation and strengthens the Mott phase. The significant reduction of the Neel temperature from 150 K for m = 1 to 40 K for m = 2 demonstrates that the long-range order stability in the former is boosted by a substantial interlayer exchange coupling. Resonant x-ray magnetic scattering revealed that the interlayer exchange coupling has a switchable sign, depending on the SrTiO3 layer number m, for maintaining canting-induced weak ferromagnetism. The nearly unaltered transition temperature between the m = 2 and the m = 3 demonstrated that we have realized a two-dimensional antiferromagnet at finite temperatures with diminishing interlayer exchange coupling.

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Model analysis of magnetic susceptibility of Sr2IrO4 : A two-dimensional Jeff=12

Cited by 25 publications

References 37 publications

Square Lattice Iridates

Square Lattice Iridates

Pseudospin-lattice coupling in the spin-orbit Mott insulator Sr2IrO4

Two-Dimensional Jeff=1/2 Antiferromagnetic Insulator Unraveled from Interlayer Exchange Coupling in Artificial Perovskite Iridate Superlattices

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