Evolution of magnetic, transport, and thermal properties in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Na</mml:mi><mml:mrow><mml:mn>4</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Ir</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:mrow></mml:math>

Balodhi, Ashiwini; Thamizhavel, A.; Singh, Yogesh

doi:10.1103/physrevb.91.224409

Cited by 16 publications

(29 citation statements)

References 28 publications

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“…An important point is that it is very difficult to accurately refine the sodium positions and occupancy because sodium has a far smaller scattering cross-section compared to iridium atoms. We did observe a small unidentifiable impurity phase (possibly IrO 2 ) found to make up approximately less than 1% of the sample as it has been reported in powder samples [22]. Powder x-ray on metallic samples yielded similar results.…”

Section: Crystal Growth and Characterisationsupporting

confidence: 83%

“…1). In other words, the peak observed at 30 K in the magnetic specific heat (and which is independent of the doping [22]) could be simply attributed to the difference in the phonon specific heat between Na 4 Ir 3 O 8 and Na 4 Sn 3 O 8 . Finally, we note that if we take the phonon contribution deduced from Na 4 Sn 3 O 8 (β pho = 0.45mJ K −4 mol −1 ), our conclusion regarding the ballistic regime in the metallic sample is not affected at all.…”

Section: Appendix C: Phonon Contribution In the Specific Heatmentioning

confidence: 99%

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Thermal conductivity across the metal-insulator transition in the single-crystalline hyperkagome antiferromagnetNa3+xIr3O8

Fauqué

Bangura

et al. 2015

Phys. Rev. B

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The hyperkagome antiferromagnet Na 4 Ir 3 O 8 represents the first genuine candidate for the realization of a three-dimensional quantum spin liquid. It can also be doped towards a metallic state, thus offering a rare opportunity to explore the nature of the metal-insulator transition in correlated, frustrated magnets. Here, we report thermodynamic and transport measurements in both metallic and weakly insulating single crystals down to 150 mK. While in the metallic sample the phonon thermal conductivity (κ ph ) is almost in the boundary scattering regime, in the insulating sample, we find a large reduction κ ph over a very wide temperature range. This result can be ascribed to the scattering of phonons off the gapless magnetic excitations that are seen in the low-temperature specific heat. This works highlights the peculiarity of the metal-insulator transition in Na 3+x Ir 3 O 8 and demonstrates the importance of the coupling between lattice and spin degrees of freedom in the presence of strong spin-orbit coupling.

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Section: Crystal Growth and Characterisationsupporting

confidence: 83%

Section: Appendix C: Phonon Contribution In the Specific Heatmentioning

confidence: 99%

Thermal conductivity across the metal-insulator transition in the single-crystalline hyperkagome antiferromagnetNa3+xIr3O8

Fauqué

Bangura

et al. 2015

Phys. Rev. B

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“…This has led theorists to promote, for example, the Heisenberg-Kitaev model [19] and the spin-orbit Mott insulator [20]. Na 4 Ir 3 O 8 also appears to be close to an insulator-metal transition [21][22][23][24][25] and weak Mottness has been proposed as a possible scenario for a spin-liquid ground state [26,27], like in the case of organic triangular spin-liquids [12].The macroscopic susceptibility, χ, is typical of J eff = 1 2 moments with antiferromagnetic interactions J ∼ 300 K [14,28]. Heat capacity, C, shows no sign of a bulk transition and has two remarkable features: at 24 K ∼ J/10 a broad maximum and at low temperatures C = γT + βT n where 2 < n < 3 [14,21].…”

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Frozen State and Spin Liquid Physics inNa4Ir3O8: An

Ac¹,

Bert²,

Jc³

et al. 2015

Phys. Rev. Lett.

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Na4Ir3O8 is a unique case of a hyperkagome 3D corner sharing triangular lattice which can be decorated with quantum spins. It has spurred a lot of theoretical interest as a spin liquid candidate. We present a comprehensive set of NMR data taken on both the 23 Na and 17 O sites. We show that disordered magnetic freezing of all Ir sites sets in below T f ∼ 7 K, well below J = 300 K, with a drastic slowing down of fluctuations to a static state revealed by our T1 measurements. Above typically 2 T f , physical properties are relevant to the spin liquid state induced by this exotic geometry. While the shift data shows that the susceptibility levels off below 80 K, 1/T1 has little variation from 300 K to 2 T f . We discuss the implication of our results in the context of published experimental and theoretical work.Geometric frustration has long been known as an essential ingredient to stabilize a quantum spin liquid (QSL) state in more than one dimension (1D) [1,2] [10], and organic compounds which are driven by proximity to a Mott transition [11,12].Currently, Na 4 Ir 3 O 8 is one of the most compelling frustrated QSL candidate in three-dimensions (3D) [13] where Ir 4+ ions with effective J eff = 1 2 form a cornersharing lattice of triangles named "hyperkagome" [14]. Strong spin-orbit coupling, SOC, has been identified as an important ingredient in the Hamiltonian. Several possible theoretical scenarios have been proposed thus far, including a classical long-ranged order-by-disorder 120 o coplanar ground state [15] which in the quantum limit melts into a gapped QSL [16] and a gapless QSL [17,18]. More generally, iridates appear as an ideal playground for the study of novel physics governed by strong SOC in competition with Coulomb repulsion, crystal field effects, and inter-site hopping. This has led theorists to promote, for example, the Heisenberg-Kitaev model [19] and the spin-orbit Mott insulator [20]. Na 4 Ir 3 O 8 also appears to be close to an insulator-metal transition [21][22][23][24][25] and weak Mottness has been proposed as a possible scenario for a spin-liquid ground state [26,27], like in the case of organic triangular spin-liquids [12].The macroscopic susceptibility, χ, is typical of J eff = 1 2 moments with antiferromagnetic interactions J ∼ 300 K [14,28]. Heat capacity, C, shows no sign of a bulk transition and has two remarkable features: at 24 K ∼ J/10 a broad maximum and at low temperatures C = γT + βT n where 2 < n < 3 [14,21]. Both χ and C suggest the presence of a gapless ground state [17,18]. Magnetocaloric measurements suggest a quantum critical behavior in zero-field [21]. Although no signs of a bulk transition exist, there is a small splitting of the field-cooled (FC) and zero field-cooled (ZFC) magnetization at T ∼ 6 K [29]. Initially, this splitting was proposed to be associated with a ∼ 1% defect or impurity term [14,21], but recent µSR measurements [29] suggest quasi-static short range spin correlations appear below T = 6 K. Probing the role of these defects on the physics of this compo...

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Unique hyper-kagome atomic order in geometrically frustrated iridium spinel-like structures

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Широков

2017

Russ Chem Bull

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Evolution of magnetic, transport, and thermal properties inNa4−xIr3O8

Cited by 16 publications

References 28 publications

Thermal conductivity across the metal-insulator transition in the single-crystalline hyperkagome antiferromagnetNa3+xIr3O8

Thermal conductivity across the metal-insulator transition in the single-crystalline hyperkagome antiferromagnetNa3+xIr3O8

Frozen State and Spin Liquid Physics inNa4Ir3O8: An

Unique hyper-kagome atomic order in geometrically frustrated iridium spinel-like structures

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