Re-examination of the structure of Ba2MIrO6 (M=La, Y): space group revised

Fu, W.T.; IJdo, D.J.W.

doi:10.1016/j.jallcom.2004.10.049

Cited by 30 publications

(45 citation statements)

References 12 publications

(25 reference statements)

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“…2) using space group F m3m for Ba 2 YIrO 6 and Ia3 for Y 2 O 3 results in refinement parameters R p = 2.54 and R wp = 3.88. The lattice constants obtained from singlecrystal XRD and powder XRD on crushed crystals are consistent with earlier reports [22][23][24][25]. We find no signature of any structural transition of the crystals from room temperature (powder XRD) down to 198(2) K (singlecrystal XRD).…”

Section: B Xrd and Crystal Structuresupporting

confidence: 91%

“…225), similar to results as reported in Refs. [22][23][24] based on XRD measurements on polycrystalline samples. The results of the structural refinement of the single-crystal XRD measurements at 198(2) K are summarized in Table I.…”

Section: B Xrd and Crystal Structurementioning

confidence: 99%

“…The crystal structure of Ba 2 YIrO 6 has been described using a cubic symmetry (space group F m3m) [22][23][24] as well as a monoclinic symmetry (space group P 2 1 /n) with β = 90.039 o (Ref. 25).…”

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confidence: 99%

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Ba2YIrO6: A cubic double perovskite material withIr5+ions

et al. 2016

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Materials with a 5d 4 electronic configuration are generally considered to have a nonmagnetic ground state (J = 0). Interestingly, Sr2YIrO6 (Ir 5+ having 5d 4 electronic configuration) was recently reported to exhibit long-range magnetic order at low temperature and the distorted IrO6 octahedra were discussed to cause the magnetism in this material. Hence, a comparison of structurally distorted Sr2YIrO6 with cubic Ba2YIrO6 may shed light on the source of magnetism in such Ir 5+ materials with 5d 4 configuration. Besides, Ir 5+ materials having 5d 4 are also interesting in the context of recently predicted excitonic types of magnetism. Here we report a single-crystal-based analysis of the structural, magnetic, and thermodynamic properties of Ba2YIrO6. We observe that in Ba2YIrO6 for temperatures down to 0.4 K, long-range magnetic order is absent but at the same time correlated magnetic moments are present. We show that these moments are absent in fully relativistic ab initio band-structure calculations; hence, their origin is presently unclear.

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Section: B Xrd and Crystal Structuresupporting

confidence: 91%

Section: B Xrd and Crystal Structurementioning

confidence: 99%

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Ba2YIrO6: A cubic double perovskite material withIr5+ions

et al. 2016

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“…A similar double perovskite Ba 2 YIrO 6 (space group Fm-3m) has lattice parameter a = 8.35032Å. 17 Atomic cell parameters for the primary phase resulting from our refinement are listed in Table I. Attempts to explain Fig.…”

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confidence: 99%

Possible spin-orbit driven spin-liquid ground state in the double perovskite phase of Ba3YIr2O9

et al. 2013

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We report the structural transformation of hexagonal Ba 3 YIr 2 O 9 to a cubic double perovskite form (stable in ambient conditions) under an applied pressure of 8 GPa at 1273 K. While the ambient pressure synthesized sample undergoes long-range magnetic ordering at ∼4 K, the high-pressure (HP) synthesized sample does not order down to 2 K as evidenced from our susceptibility, heat capacity, and nuclear magnetic resonance (NMR) measurements. Further, for the HP sample, our heat capacity data have the form γ T + βT 3 in the temperature (T ) range of 2-10 K with the Sommerfeld coefficient γ = 10 mJ/mol-Ir K 2 . The 89 Y NMR shift has no T dependence in the range of 4-120 K and its spin-lattice relaxation rate varies linearly with T in the range of 8-45 K (above which it is T independent). Resistance measurements of both the samples confirm that they are semiconducting. Our data provide evidence for the formation of a 5d-based, gapless, quantum spin-liquid in the cubic (HP) phase of Ba 3 YIr 2 O 9 . In this picture, the γ T term in the heat capacity and the linear variation of 89 Y 1/T 1 arises from excitations out of a spinon Fermi surface. Our findings lend credence to the theoretical suggestion [Chen, Pereira, and Balents, Phys. Rev. B 82, 174440 (2010) 9 It will be interesting to explore other iridates having a triangular lattice. Ba 3 YIr 2 O 9 has a similar chemical formula like Ba 3 IrTi 2 O 9 and it crystallizes in the hexagonal structure (P6 3 /mmc) with Ir-Ir structural dimers arranged in an edge-shared triangular fashion.10 Since all the Ir are equivalent, they should have a fractional oxidation state of +4.5 in a simple ionic picture. Our investigation of this 5d-based system is motivated by the fact that the fractional valence coupled with a geometrically frustrated lattice might lead to a spin-liquid state or possibly a heavy fermion state as in the 3d-based LiV 2 O 4 .11 This however did not turn out to be the case. Whereas we confirmed the onset of long-range order below 4 K in Ba 3 YIr 2 O 9 (in agreement with Ref. 10), we succeeded in suppressing the magnetic order with the application of pressure. In fact, when Ba 3 YIr 2 O 9 was subjected to a pressure of 8 GPa at 1273 K, it transformed to a cubic double perovskite structure as evidenced from x-ray diffraction under ambient conditions. Though the high-pressure (HP) synthesized sample remains insulating (based on our resistivity measurements), it has a metal-like linear heat capacity coefficient γ = 10 mJ/mol-Ir K 2 . Further, the 89 Y nuclear magnetic resonance (NMR) shift is found to be independent of temperature (T ) below 120 K and the 89 Y NMR spin-lattice relaxation rate crosses over from T -independent behavior at high temperature to a linear T dependence below about 45 K. These results point to the existence of low-energy excitations at low temperatures. In the absence of metallic behavior in the resistivity and the presence of local moments, the low-T data suggest the formation of an exotic ground state for the HP phase, possibly a gaple...

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“…Because the crystal structure is an important prerequisite for understanding its properties, many experimental efforts were given in this aspect. For the title compounds, they were synthesized by solid state reaction method at high temperatures [2][3][4][5]. We will introduce the details in the following section.…”

Section: Introductionmentioning

confidence: 99%