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Bera, A. K.; Yusuf, S. M.; Kumar, Amit; Ritter, C.

doi:10.1103/physrevb.95.094424

Cited by 103 publications

(105 citation statements)

References 62 publications

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“…The observation of a broad diffuse peak provides direct evidence for the presence of SRO AFM spin clusters. A similar broad diffuse peak has been reported in geometrically frustrated pyrochlores [94,95], spin-chain compounds [96,97], and spinels [98] showing CSG freezing.…”

Section: F Direct Evidence For the Presence Of Spin Clusters In Cfn supporting

confidence: 80%

“…Neutron-scattering technique can provide evidence not only for the presence of LRO AFM structure but also for short-range ordered (SRO) AFM clusters of spins in the CSG systems. The presence of SRO AFM spin clusters gives rise to diffuse scattering in the neutron-scattering patterns [46,74,[94][95][96][97][98]. Accordingly, we carried out NPD measurements on powder samples of CFN to obtain direct evidence for the presence of AFM spin clusters.…”

Section: F Direct Evidence For the Presence Of Spin Clusters In Cfn mentioning

confidence: 99%

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Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2
Kumar
¹
,
Senyshyn
²
,
Pandey
³

2019
Phys. Rev. B
39
7
21
0
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The origin of the spin glass (SG) phase in the well-known multiferroic Pb(Fe 1/2 Nb 1/2)O 3 compound remains controversial due to the complications introduced by the coexistence of SG and long-range ordered (LRO) antiferromagnetic (AFM) phases. We have addressed this controversy through a comprehensive study on a Pb-free system Ca(Fe 1/2 Nb 1/2)O 3 (CFN) which does not exhibit LRO AFM transition. The SG transition in CFN is confirmed by the appearance of a cusp in the temperature dependence of dc magnetization M(T) with a SG freezing temperature T f ∼ 25 K, and bifurcation of the zero-field-cooled and field-cooled magnetization M(T) below the irreversibility temperature T irr ∼ 27 K. Using ac susceptibility [χ (ω, T)] measurements, we show that the spin dynamics follows power/Vogel-Fulcher law-type critical dynamics which diverges at T SG ∼ 24 K with an attempt time τ o ∼ 10 −6 s suggesting cluster spin glass (CSG) behavior. The field dependence of T f (H) and T irr (H) is shown to follow the de Almeida-Thouless line which separates the ergodic and nonergodic phases in the H-T plane and gives T f (H = 0) ∼ 25 K, which is in close agreement with T SG obtained from χ (ω, T). The existence of the glassy phase below T SG is further confirmed by the observation of slow nonexponential decay of thermoremanent magnetization with time, memory and rejuvenation effects, and unidirectional exchange-bias effect in the M-H hysteresis loop of field-cooled samples. The neutron powder-diffraction patterns reveal the absence of any magnetic peak due to LRO AFM phase but show a broad diffuse peak due to the presence of ∼ 2-nm-size AFM spin clusters which are responsible for the CSG freezing in CFN.

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Section: F Direct Evidence For the Presence Of Spin Clusters In Cfn supporting

confidence: 80%

Section: F Direct Evidence For the Presence Of Spin Clusters In Cfn mentioning

confidence: 99%

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2
Kumar
¹
,
Senyshyn
²
,
Pandey
³

2019
Phys. Rev. B
39
7
21
0
View full text Add to dashboard Cite

show abstract

“…One of the major challenges in Na-ion batteries is to design improved materials for better efficiency. In this regard, the family of Na based compounds Na2X2TeO6 (where X = Co, Ni, Zn, Mg, and Fe) has drawn good attention in recent years [4][5][6][7][8] . These compounds are reported to have significant Na conductivity at room temperature, suitable for application in a Na-ion battery 4 .…”

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Na-Ion Conduction and Its Pathways in the Crystal Structure of the Layered Battery Material Na₂Ni₂TeO₆

Bera

Yusuf

2020

J. Phys. Chem. C

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Na-ion conduction, and correlations between Na-ion conduction pathways and crystal structure have been investigated as a function of temperature in the layered battery material Na2Ni2TeO6 by impedance spectroscopy and neutron diffraction, respectively. The impedance data reveal an ionic conductivity  210-4 S/m at 323 K which strongly enhances with increasing temperature and attains a high value of ~ 0.03 S/m at 423 K. The temperature dependent conductivity data show an Arrhenius type behavior with average activation energy (Ea) of ~ 0.58(3) eV for T  383 K. By employing soft-bond valence sum analysis of the neutron diffraction patterns we experimentally demonstrate the site-specific Na-ion conductions, through visualization of microscopic sodium-ion conduction pathways, and verify the recent theoretical results of Molecular dynamic simulation. Our results reveal two-dimensional Na-ion conduction pathways that are confined within the ab planes of Na layers. Crystal structural study indicates that the layered structure involving Na ion layers is responsible for high ionic conductivity, and the local crystallographic environment of Na ion sites is responsible for site-specific conductivity. Our study further reveals that up to 500 K, the ionic conduction is governed by the Na ions located at the Na1 and Na2 sites, whereas, all the Na ions located at the three Na-sites contribute to the conduction process above 500 K. Our neutron diffraction study also establishes that the crystal structure of Na2Ni2TeO6 is stable at least up to 725 K (the highest measured temperature), however, with an anisotropic thermal expansion (c/a ~ 3).

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“…Honeycomb lattice cobaltates.-A number of such compounds are known: A 3 Co 2 SbO 6 (A ¼ Na; Ag; Li) [18][19][20]43,44], Na 2 Co 2 TeO 6 [18,[45][46][47], BaCo 2 ðXO 4 Þ 2 (X ¼ As, P) [48][49][50][51], CoTiO 3 [52][53][54], CoPS 3 [55,56]. They are quasi-two-dimensional magnets; within the ab planes, zigzag or FM order is most common.…”

mentioning

confidence: 99%

Kitaev Spin Liquid in 3d Transition Metal Compounds

2020

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We study the exchange interactions and resulting magnetic phases in the honeycomb cobaltates. For a broad range of trigonal crystal fields acting on Co 2þ ions, the low-energy pseudospin-1=2 Hamiltonian is dominated by bond-dependent Ising couplings that constitute the Kitaev model. The non-Kitaev terms nearly vanish at small values of trigonal field Δ, resulting in spin liquid ground state. Considering Na 3 Co 2 SbO 6 as an example, we find that this compound is proximate to a Kitaev spin liquid phase, and can be driven into it by slightly reducing Δ by ∼20 meV, e.g., via strain or pressure control. We argue that, due to the more localized nature of the magnetic electrons in 3d compounds, cobaltates offer the most promising search area for Kitaev model physics.

show abstract

Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-two-dimensional honeycomb lattice compoundNa2Co2TeO6

Abstract: The crystal structure, magnetic ground state, and the temperature dependent

Cited by 103 publications

References 62 publications

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2
Kumar
¹
,
Senyshyn
²
,
Pandey
³

2019
Phys. Rev. B
39
7
21
0
View full text Add to dashboard Cite

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2
Kumar
¹
,
Senyshyn
²
,
Pandey
³

2019
Phys. Rev. B
39
7
21
0
View full text Add to dashboard Cite

Temperature-Dependent Na-Ion Conduction and Its Pathways in the Crystal Structure of the Layered Battery Material Na₂Ni₂TeO₆

Kitaev Spin Liquid in 3d Transition Metal Compounds

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Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-two-dimensional honeycomb lattice compoundNa2Co2TeO6

Abstract: The crystal structure, magnetic ground state, and the temperature dependent

Cited by 103 publications

References 62 publications

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2Kumar1, Senyshyn2, Pandey3 2019Phys. Rev. B397210View full textAdd to dashboardCite

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2Kumar1, Senyshyn2, Pandey3 2019Phys. Rev. B397210View full textAdd to dashboardCite

Temperature-Dependent Na-Ion Conduction and Its Pathways in the Crystal Structure of the Layered Battery Material Na2Ni2TeO6

Kitaev Spin Liquid in 3d Transition Metal Compounds

Contact Info

Product

Resources

About

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2
Kumar
¹
,
Senyshyn
²
,
Pandey
³

2019
Phys. Rev. B
39
7
21
0
View full text Add to dashboard Cite

Evidence for cluster spin glass phase with precursor short-range antiferromagnetic correlations in the B -site disordered Ca(Fe1/2
Kumar
¹
,
Senyshyn
²
,
Pandey
³

2019
Phys. Rev. B
39
7
21
0
View full text Add to dashboard Cite

Temperature-Dependent Na-Ion Conduction and Its Pathways in the Crystal Structure of the Layered Battery Material Na₂Ni₂TeO₆