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Zhao, Songrui; Mackie, J. M.; MacLaughlin, D. E.; Bernal, O. O.; Ishikawa, Jun; Ohta, Yasuo; Nakatsuji, Satoru

doi:10.1103/physrevb.83.180402

Cited by 91 publications

(122 citation statements)

References 41 publications

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“…9,17,23,25,37,38 Therefore, to clarify the fundamental magnetic properties associated with the iridium tetrahedral network, it is desired to choose the compounds with non-magnetic A-site ions, e.g. Eu 3+ , 18,19 Bi 3+ , [26][27][28][29] and Y 3+ .…”

Section: 34mentioning

confidence: 99%

Enhanced weak ferromagnetism and conductivity in hole-doped pyrochlore iridateY2Ir2O7

et al. 2014

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Pyrochlore iridates have recently attracted growing interest in condensed matter physics because of their potential for realizing new topological states. In order to achieve such quantum states, it is essential to understand the magnetic properties of these compounds, as their electronic structures are strongly coupled with their magnetic ground states. In this work, we report a systematic study of the magnetic properties of pyrochlore Y 2 Ir 2 O 7 and its hole-doped compounds by performing magnetic, electron spin resonance (ESR), electrical transport and x-ray photoelectron spectroscopy (XPS) measurements. We demonstrate the existence of weak ferromagnetism on top of a large antiferromagnetic background in the undoped compound. Hole-doping by calcium was found to enhance both the ferromagnetism and the electrical conductivity. The XPS characterization shows the coexistence of Ir 4+ and Ir 5+ in the undoped compound, and the amount of Ir 5+ increases with Ca-doping, which highlights the possible origins of the weak ferromagnetism associated with the formation of Ir 5+ . We also observe a vertical shift in the M -H curves after field cooling, which may arise from a strong coupling between the ferromagnetic phase and the antiferromagnetic background.

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Section: 34mentioning

confidence: 99%

Enhanced weak ferromagnetism and conductivity in hole-doped pyrochlore iridateY2Ir2O7

et al. 2014

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“…No thermal hysteresis effect can be observed at T MI (T N ), thus, indicating a second order transition [9]. At T N , magnetization, µSR and resonant X-ray scattering experiments suggest an ordering of the Ir 4+ moments [9,[11][12][13][14]. At lower temperatures, the d − f interaction may induce the magnetic ordering at the R site (also depending on the single-ion anisotropy at the R site [15] [17,18].…”

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confidence: 95%

Direct determination of the spin structure ofNd2Ir2O7by means of neutron diffraction

2016

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We report on the spin structure of the pyrochlore iridate Nd 2 Ir 2 O 7 that could be directly determined by means of powder neutron diffraction. Our magnetic structure refinement unravels a so-called all-in/all-out magnetic structure that appears in both, the Nd and the Ir sublattice. The ordered magnetic moments at 1.8 K amount to 0.34(1) µ B /Ir 4+ and 1.27(1) µ B /Nd 3+ . The Nd 3+ moment size at 1.8 K is smaller than that expected for the Nd 3+ ground state doublet. On the other hand, the size of the ordered moments of the Ir 4+ ions at 1.8 K agrees very well with the value expected for a J eff = 1/2 state based on the presence of strong spin-orbit coupling in this system. Finally, our measurements reveal a parallel alignment of the Nd 3+ moments with the net moment of its six nearest neighboring Ir 4+ ions.PACS numbers: 75.25. 75.30.Gw, 75.47.Lx, 71.70.Ej The 5d transition metal oxides have attracted substantial attention due to the interplay between the relatively large spinorbit coupling (SOC) and electron-electron correlations (U), which may result in exotic electronic phases such as topological Mott insulators, Weyl semimetals and axion insulators [1][2][3][4][5][6][7]. The pyrochlore iridates (R 2 Ir 2 O 7 , R = rare earth and Y) are a fertile playground to realize these topological phases. For the pyrochlore structure, the ions at the R site or Ir site form a network of corning-sharing tetrahedra with the two sublattices penetrating each other. These pyrochlore iridates exhibit a metal-insulator transition (MIT) at T MI which continuously decreases with increasing R-ionic radius. The MIT disappears (T MI = 0) between R = Nd and Pr [8][9][10]. No thermal hysteresis effect can be observed at T MI (T N ), thus, indicating a second order transition [9]. At T N , magnetization, µSR and resonant X-ray scattering experiments suggest an ordering of the Ir 4+ moments [9,[11][12][13][14]. At lower temperatures, the d − f interaction may induce the magnetic ordering at the R site (also depending on the single-ion anisotropy at the R site [15] [17,18]. It was shown that a quantum MIT is realized when a magnetic field of ∼10 T is applied only along the [0 0 1] direction, with the ground state changing from an insulating magnetic ordered state to a semimetal state [17,18]. This could be explained by a reconstruction of the band structure concomitant with the change of the magnetic structure in the Nd sublattice from an all-in/all-out (AIAO) to a two-in/two-out magnetic structure.Several theoretical calculations [1][2][3][4][5]7] have demonstrated that the AIAO magnetic structure has the lowest energy when U becomes larger than a critical value U c . The AIAO magnetic ordering is also indispensable for realizing the topologically nontrivial Weyl semimetal state [1][2][3][4][5]7]. Therefore, it is essential to unambiguously determine the magnetic structure of Nd 2 Ir 2 O 7 experimentally in order to understand these emergent phenomena in pyrochlore iridates. Apart from the Nd sublattice where an AIAO magnetic st...

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“…However, due to the narrowed J eff = 1/2 band-width, the smaller 5d U is capable of inducing Mott insulating behavior, as seen in Sr 2 IrO 4 7 and Na 2 IrO 3 8 . Pr 2 Ir 2 O 7 is part of a family of pyrochlore iridates, R 2 Ir 2 O 7 that undergo a metal-insulator transition (MIT) as a function of the rare-earth element [9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Chiral RKKY interaction in Pr2Ir2O7

Flint

Senthil

2013

Phys. Rev. B

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Motivated by the potential chiral spin liquid in the metallic spin ice Pr2Ir2O7, we consider how such a chiral state might be selected from the spin ice manifold. We propose that chiral fluctuations of the conducting Ir moments promote ferro-chiral couplings between the local Pr moments, as a chiral analogue of the magnetic RKKY effect. Pr2Ir2O7 provides an ideal setting to explore such a chiral RKKY effect, given the inherent chirality of the spin-ice manifold. We use a slave-rotor calculation on the pyrochlore lattice to estimate the sign and magnitude of the chiral coupling, and find it can easily explain the 1.5K transition to a ferro-chiral state.

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Magnetic transition, long-range order, and moment fluctuations in the pyrochlore iridate Eu2Ir2O

Cited by 91 publications

References 41 publications

Enhanced weak ferromagnetism and conductivity in hole-doped pyrochlore iridateY2Ir2O7

Enhanced weak ferromagnetism and conductivity in hole-doped pyrochlore iridateY2Ir2O7

Direct determination of the spin structure ofNd2Ir2O7by means of neutron diffraction

Chiral RKKY interaction in Pr2Ir2O7

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