Evolution of electronic and magnetic properties in a series of iridate double perovskites 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Pr</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>MgIrO</mml:mi><mml:mn>6</mml:mn></mml:msub><mml:mo> </mml:mo><mml:mo>(</mml:mo><mml:mi>x</mml:mi><mml:mo>=</mml:mo><mml:mn>0</mml:mn><mml:mo>,</mml:mo><mml:mn>0.5

Bandyopadhyay, A.; Carlomagno, Ilaria; Simonelli, Laura; Sala, M. Moretti; Efimenko, Anna; Meneghini, Carlo; Ray, Sugata

doi:10.1103/physrevb.100.064416

Cited by 16 publications

(26 citation statements)

References 54 publications

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“…The peak shape, structure, and the relative peak intensity corresponding to 2p → t 2g transition (inset to Fig. 3(a)) strongly affirm pure 5+ oxidation state of Ir [10,45,46] in SLIO.…”

Section: B Theoretical Methodsmentioning

confidence: 64%

“…The origin of such a large Ir 5+ -moment in SLIO could certainly be attributed to the intersite Ir-Ir hopping via extended Ir-O-O-Ir superexchange pathways within all possible intra and interchain magnetic exchange connectivity (represented by three different exchange interactions in Fig. 1 (b)), causing delocalization of intra-site Ir 5+ holes, and therefore, creating deviation from a perfect atomic J = 0 arrangement [10,47,48]. In addition, the trigonal distortion of the IrO 6 octahedra and the subsequent Ir-t 2g splitting, as well as the hybridization of extended Ir-5d orbitals and the stronger Ir-O covalent interactions together might cause rearrangement in the spin-orbit coupled Ir energy levels in SLIO, and as a result, leading to the possible breakdown of atomic J limit [63][64][65][66].…”

Section: E DC Magnetic Susceptibility and Spin Polarized Dft Calculat...mentioning

confidence: 99%

“…In this context, it is of interest to explore the enhanced quan- * email:mssr@iacs.res.in tum fluctuations of the spin-orbital entangled states of the geometrically frustrated 5d Ir-oxides. Here one of the most discussed prevailing controversy in the context of pentavalent d 4 (Ir 5+ :5d 4 ) iridates is the deviation of ideally nonmagnetic J = 0 state under strong SOC limit, and the concomitant development of finite Ir-magnetic moments [6][7][8][9][10][11] and QSL in these systems.…”

Section: Introductionmentioning

confidence: 99%

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Sr$_3$LiIrO$_6$: a potential quantum spin liquid candidate in the one dimensional $d^4$ iridate family

Bandyopadhyay¹,

Chakraborty²,

Bhowal³

et al. 2021

Preprint

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Spin-orbit coupling (SOC) offers a large variety of novel and extraordinary magnetic and electronic properties in otherwise 'ordinary pool' of heavy ion oxides. Here we present a detailed study on an apparently isolated hexagonal 2H spin-chain d 4 iridate Sr3LiIrO6 (SLIO) with geometric frustration. Our structural studies clearly reveal perfect Li-Ir chemical order in this compound. Our combined experimental and ab-initio electronic structure investigations establish a magnetic ground state with finite Ir 5+ magnetic moments in this compound, contrary to the anticipated nonmagnetic J=0 state. Furthermore, the dc magnetic susceptibility (χ), heat capacity (Cp) and spin-polarized density functional theory (DFT) studies unravel that despite having noticeable antiferromagnetic correlation among the Ir 5+ local moments, this SLIO system evades any kind of magnetic ordering down to at least 2 K due to geometrical frustration, arising from the comparable interchain Ir-O-O-Ir superexchange interaction strengths, hence promoting SLIO as a potential quantum spin liquid candidate.

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“…The peak shape, structure, and the relative peak intensity corresponding to 2p → t 2g transition (inset to Fig. 3(a)) strongly affirm pure 5+ oxidation state of Ir [10,45,46] in SLIO.…”

Section: B Theoretical Methodsmentioning

confidence: 64%

Section: E DC Magnetic Susceptibility and Spin Polarized Dft Calculat...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sr$_3$LiIrO$_6$: a potential quantum spin liquid candidate in the one dimensional $d^4$ iridate family

Bandyopadhyay¹,

Chakraborty²,

Bhowal³

et al. 2021

Preprint

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“…The lower energy peak (11215.06 eV) corresponds to Ir 2p → t 2g transition and the higher energy peak (11218.73 eV) signifies Ir 2p → e g transition. It should be noted that neither the Ir 2p → t 2g nor the Ir 2p → e g peaks does show any noticeable chemical shift in any of the measured temperatures with respect to the IrO 2 spectrum, thus suggesting pure 4+ valence of Ir in this compound [45]. Moreover, the ratio of areas under the Ir 2p → t 2g and Ir 2p → e g peaks does not reveal any change in the measured spectra of Eu 2 Ir 2 O 7 relative to the reference IrO 2 oxide, hence rejecting any possibility of Ir-valence-change and/or Irmixed valency in the Eu 2 Ir 2 O 7 compound down to the lowest measured temperature.…”

Section: B X-ray Absorption Near Edge Structurementioning

confidence: 80%

The interplay between structural, magnetic and electronic states in the pyrochlore iridate Eu2Ir2O7

Das,

Bhowal,

Sannigrahi

et al. 2022

Preprint

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We address the concomitant metal-insulator transition (MIT) and antiferromagnetic ordering in the novel pyrochlore iridate Eu2Ir2O7 by combining x-ray absorption spectroscopy, x-ray and neutron diffractions and density functional theory (DFT) based calculations. The temperature dependent powder x-ray diffraction clearly rules out any change in the lattice symmetry below the MIT, nevertheless a clear anomaly in the Ir-O-Ir bond angle and Ir-O bond length is evident at the onset of MIT. From the x-ray absorption near edge structure (XANES) spectroscopic study of Ir-L3 and L2 edges, the effective spin-orbit coupling is found to be intermediate, at least quite far from the strong atomic spin-orbit coupling limit. Powder neutron diffraction measurement is in line with an allin-all-out magnetic structure of the Ir-tetrahedra in this compound, which is quite common among rare-earth pyrochlore iridates. The sharp change in the Ir-O-Ir bond angle around the MIT possibly arises from the exchange striction mechanism, which favors an enhanced electron correlation via weakening of Ir-Ir orbital overlap and an insulating phase below TMI . The theoretical calculations indicate an insulating state for shorter bond angle validating the experimental observation. Our DFT calculations show a possibility of intriguing topological phase below a critical value of the Ir-O distance, which is shorter than the experimentally observed bond length. Therefore, a topological state may be realized in bulk Eu2Ir2O7 sample if the Ir-O bond length can be reduced by the application of sufficient external pressure.

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“…Similarly, an AFM to FiM spin ordering transition is observed in system due to -doping and authors claimed that changes in the microscopic magnetic interaction may be associated with the mixed-valence state of Ir 38 . In a similar fashion, system exhibits a transition from Mott-insulating to HM AFM state at , where Ir-ion remains in mixed-valence states of , , and for , , and samples, respectively 45 . Moreover, Coutrim et al, experiments show that variations of the magnetic coupling between Co and Ir ions in are due to a change of their valence, when La is replaced with Ca ion having a concentration of Ca 40 .…”

Section: Introductionmentioning

confidence: 80%

Insulator-to-half metal transition and enhancement of structural distortions in $$\text {Lu}_2 \text {NiIrO}_6$$ double perovskite oxide via hole-doping

Nazir

2021

Sci Rep

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Using density functional theory calculations, we found that recently high-pressure synthesized double perovskite oxide $$\text {Lu}_2 \text {NiIrO}_6$$ Lu 2 NiIrO 6 exhibits ferrimagnetic (FiM) Mott-insulating state having an energy band gap of 0.20 eV which confirms the experimental observations (Feng et al. in Inorg Chem 58:397–404, 2019). Strong antiferromagnetic superexchange interactions between high-energy half-filled $$\text {Ni}^{+2}$$ Ni + 2 -$$e_g^2\uparrow$$ e g 2 ↑ and low-energy partially filled $$\text {Ir}^{+4}\,t_{2g}^3\uparrow t_{2g}^2\downarrow$$ Ir + 4 t 2 g 3 ↑ t 2 g 2 ↓ orbitals, results in a FiM spin ordering. Besides, the effect of 3d transition metal (TM = Cr, Mn, and Fe) doping with 50% concentration at Ni sites on its electronic and magnetic properties is explored. It is established that smaller size cation-doping at the B site enhances the structural distortion, which further gives strength to the FiM ordering temperature. Interestingly, our results revealed that all TM-doped structures exhibit an electronic transition from Mott-insulating to a half-metallic state with effective integral spin moments. The admixture of Ir 5d orbitals in the spin-majority channel are mainly responsible for conductivity, while the spin minority channel remains an insulator. Surprisingly, a substantial reduction and enhancement of spin moment are found on non-equivalent Ir and oxygen ions, respectively. This leads the Ir ion in a mixed-valence state of $$+4$$ + 4 and $$+5$$ + 5 in all doped systems having configurations of $$5d^5$$ 5 d 5 ($$t_{2g}^3\uparrow t_{2g}^2\downarrow$$ t 2 g 3 ↑ t 2 g 2 ↓ ) and $$5d^4$$ 5 d 4 ($$t_{2g}^2\uparrow t_{2g}^2\downarrow$$ t 2 g 2 ↑ t 2 g 2 ↓ ), respectively. Hence, the present work proposes that doping engineering with suitable impurity elements could be an effective way to tailor the physical properties of the materials for their technological potential utilization in advanced spin devices.

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Evolution of electronic and magnetic properties in a series of iridate double perovskites Pr2−xSrxMgIrO6 (x=0,0.5

Cited by 16 publications

References 54 publications

Sr$_3$LiIrO$_6$: a potential quantum spin liquid candidate in the one dimensional $d^4$ iridate family

Sr$_3$LiIrO$_6$: a potential quantum spin liquid candidate in the one dimensional $d^4$ iridate family

The interplay between structural, magnetic and electronic states in the pyrochlore iridate Eu2Ir2O7

Insulator-to-half metal transition and enhancement of structural distortions in $$\text {Lu}_2 \text {NiIrO}_6$$ double perovskite oxide via hole-doping

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