Misjudging frustrations in spin liquids from oversimplified use of Curie-Weiss law

Nag, Abhishek; Ray, Sugata

doi:10.1016/j.jmmm.2016.10.014

Cited by 17 publications

(12 citation statements)

References 39 publications

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“…Further, certain ambiguity in the AFM interaction strengths [by means of different values of negative θ CW at the different applied magnetic fields, as revealed by the respective Curie-Weiss fittings, shown in Fig. 5(a)] is also evident in SLIO, likely in consistent with many other existing QSL systems [8,47,48,57].…”

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

confidence: 76%

“…5(c), clearly reveal absence of coercivity and remanent magnetization even at the lowest measured temperature of 2 K, but the slight nonlinearity probably supports the development of spin correlations in SLIO at low temperatures, quite common in d 4 iridates [44,55,56]. Now in such disordered magnetic system, it should be worthwhile to state that within weak temperature-dependence of the measured dc susceptibility, the Curie-Weiss (C-W) fit- ting parameters always carry some uncertainties which critically depend on both the temperature range of C-W fitting and the applied magnetic fields of measurement [57]. Considering all the possibilities, the C-W analysis (χ = χ 0 + CW (T −ΘCW ) with χ 0 being the temperature independent paramagnetic susceptibility, and C W , Θ CW , the Curie constant and the Curie-Weiss temperature, respectively) on the 10 kOe field-cooled χ(T ) data seems to be most reasonable in the temperature range 100-400 K (see Fig.…”

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

confidence: 97%

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

confidence: 76%

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

confidence: 97%

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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“…This suggests that Li + @C 60 •− radicals are involved in the magnetic reactions. Fitting the ( χ − χ 0 ) − 1 to the Curie–Weiss law at high temperatures ( T > 175 K) yields a large negative Curie–Weiss temperature, θ cw = −190 K, suggesting strong antiferromagnetic (AF) interactions between the spins ( χ 0 is defined as core diamagnetic or Van–Vleck paramagnetic susceptibility 44 and determined to be 8.8 × 10 − 4 cm 3 mol − 1 in Supporting Information Fig. 7 ).…”

Section: Resultsmentioning

confidence: 99%

Heterospin frustration in a metal-fullerene-bonded semiconductive antiferromagnet

et al. 2022

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Lithium-ion-encapsulated fullerenes (Li+@C60) are 3D superatoms with rich oxidative states. Here we show a conductive and magnetically frustrated metal–fullerene-bonded framework {[Cu4(Li@C60)(L)(py)4](NTf2)(hexane)}n (1) (L = 1,2,4,5-tetrakis(methanesulfonamido)benzene, py = pyridine, NTf2− = bis(trifluoromethane)sulfonamide anion) prepared from redox-active dinuclear metal complex Cu2(L)(py)4 and lithium-ion-encapsulated fullerene salt (Li+@C60)(NTf2−). Electron donor Cu2(L)(py)2 bonds to acceptor Li+@C60 via eight Cu‒C bonds. Cu–C bond formation stems from spontaneous charge transfer (CT) between Cu2(L)(py)4 and (Li+@C60)(NTf2−) by removing the two-terminal py molecules, yielding triplet ground state [Cu2(L)(py)2]+(Li+@C60•−), evidenced by absorption and electron paramagnetic resonance (EPR) spectra, magnetic properties and quantum chemical calculations. Moreover, Li+@C60•− radicals (S = ½) and Cu2+ ions (S = ½) interact antiferromagnetically in triangular spin lattices in the absence of long-range magnetic ordering to 1.8 K. The low-temperature heat capacity indicated that compound 1 is a potential candidate for an S = ½ quantum spin liquid (QSL).

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“…However, in spite of strong SOC, the dc magnetic susceptibility measured in 3 T field (Fig. 1(d)), having qualitative similarity to paramagnets, shows presence of tiny magnetic moments which do not order down to 2 K. From a careful analysis using Curie-Weiss fits [21,25], we obtained an effective moment of around 0.3 µ B /Ir and antiferromagnetic exchanges (θ W ∼ -10 K), in this proposed J = 0 system [21].…”

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Origin of magnetic moments and presence of spin-orbit singlets in Ba2YIrO6

et al. 2018

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While it was speculated that 5d 4 systems would possess non-magnetic J = 0 ground state due to strong Spin-Orbit Coupling (SOC), all such systems have invariably shown presence of magnetic moments so far. A puzzling case is that of Ba 2 YIrO 6 , which in spite of having a perfectly cubic structure with largely separated Ir 5+ (d 4 ) ions, has consistently shown presence of weak magnetic moments. Moreover, we clearly show from Muon Spin Relaxation (µSR) measurements that a change in the magnetic environment of the implanted muons in Ba 2 YIrO 6 occurs as temperature is lowered below 10 K. This observation becomes counterintuitive, as the estimated value of SOC obtained by fitting the RIXS spectrum of Ba 2 YIrO 6 with an atomic j − j model is found to be as high as 0.39 eV, meaning that the system within this model is neither expected to possess moments nor exhibit temperature dependent magnetic response. Therefore we argue that the atomic j − j coupling description is not sufficient to explain the ground state of such systems, where despite having strong SOC, presence of hopping triggers delocalisation of holes, resulting in spontaneous generation of magnetic moments. Our theoretical calculations further indicate that these moments favour formation of spin-orbital singlets in the case of Ba 2 YIrO 6 , which is manifested in µSR experiments measured down to 60 mK.

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Misjudging frustrations in spin liquids from oversimplified use of Curie-Weiss law

Cited by 17 publications

References 39 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

Heterospin frustration in a metal-fullerene-bonded semiconductive antiferromagnet

Origin of magnetic moments and presence of spin-orbit singlets in Ba2YIrO6

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