Gapless Spin Liquid Ground State in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>S</mml:mi><mml:mo mathvariant="bold">=</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:math>Vanadium Oxyfluoride Kagome Antiferromagnet<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo stretchy="true">[</mml:mo><mml:msub><mml:mi>NH</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mo stretchy="true">]</mml:mo><mml:mn>2</mml:mn></mml:m

Clark, L. Pierce; Orain, Jean-Christophe; Bert, F.; Vries, Mark de; Aidoudi, Farida H.; Morris, Russell E.; Lightfoot, Philip; Lord, J. S.; Telling, Mark; Bonville, P.; Attfield, J. Paul; Mendels, P.; Harrison, Andrew

doi:10.1103/physrevlett.110.207208

Cited by 128 publications

(101 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4(b), which shows only a broad peak around ∼15 K followed by a decay around 30 K. A fit of the magnetic heat capacity (C m ¼ γT þ βT 2 ) at a comparatively higher temperature range (3-9 K) roughly gives a strong T-linear contribution of γ ¼ 25.9 mJ=mol K 2 , unusual for insulating systems. Also, the finite γ value does not change with application of external magnetic field as high as 90 kOe, suggesting its origin to be gapless excitations from spinon density of the QSOL state or minor lattice oxygen vacancies, but not any paramagnetic impurity [27][28][29][30][31], as seen in other spin liquid systems too [32][33][34][35]. The magnetic entropy obtained by integrating C m =T with T is shown in Fig.…”

Section: -3mentioning

confidence: 99%

Origin of the Spin-Orbital Liquid State in a NearlyJ=0IridateBa3ZnIr2O9

et al. 2016

Self Cite

View full text Add to dashboard Cite

We show using detailed magnetic and thermodynamic studies and theoretical calculations that the ground state of Ba 3 ZnIr 2 O 9 is a realization of a novel spin-orbital liquid state. Our results reveal that Ba 3 ZnIr 2 O 9 with Ir 5þ (5d 4 ) ions and strong spin-orbit coupling (SOC) arrives very close to the elusive J ¼ 0 state but each Ir ion still possesses a weak moment. Ab initio density functional calculations indicate that this moment is developed due to superexchange, mediated by a strong intradimer hopping mechanism. While the Ir spins within the structural Ir 2 O 9 dimer are expected to form a spin-orbit singlet state (SOS) with no resultant moment, substantial frustration arising from interdimer exchange interactions induce quantum fluctuations in these possible SOS states favoring a spin-orbital liquid phase down to at least 100 mK. DOI: 10.1103/PhysRevLett.116.097205 5d transition metal compounds often exhibit unusual electronic and magnetic properties due to the presence of strong spin-orbit coupling (SOC), comparable to their onsite Coulomb (U) and crystal field (Δ CFE ) interactions [1,2]. In the strong spin-orbit coupling regime, M J ( P m j ) becomes the only valid quantum number instead of m l (orbital) and m s (spin), and the multiplets and their degeneracies are solely determined by the total angular momentum J. The electronic and magnetic responses of a system in such limits are not yet well understood and have generated significant curiosity in recent times. For example, the curious insulating state of the layered tetravalent iridates (Ir 4þ ; 5d 5 ) has recently been explained within single particle theories assuming splitting of t 2g bands into a set of fully filled quartet bands separated from another set of half-filled narrow doublet bands due to finite SOC. The half-filled doublet bands further split into fully occupied lower and empty upper Hubbard bands in the presence of relatively small Hubbard U [3-5].The pentavalent Iridates (Ir 5þ ; 5d 4 ) are more intriguing, where in the strong SOC limit all the spin-orbit entangled electrons will be confined to singlet J ¼ 0 (M J ¼ 0) ground state, with no net moment. The evolution of ground and excited states of a low spin 5d t 4 2g Ir 5þ ion as a function of SOC parameter λ 0 is illustrated in Fig. 1(a) and a J ¼ 0 ground state is realized in the strong SOC limit [6]. A possibility of excitonic magnetism has been predicted for these systems where the energy scale of the singlet-triplet splitting determined by SOC is comparable to superexchange interaction promoted by hopping [10]. The breakdown of the J ¼ 0 nonmagnetic state in d 4 systems can also be realized within a single electron picture primarily driven by band-structure effect that allows the hybridization between the quartet and the doublet redistributed orbitals (eigenstates of the spin-orbit coupled Hamiltonian). Overall, d 4 Ir compounds in the strong SOC limit may host weak magnetic moment unless the λ 0 becomes so large that any excitonic or hopping-assisted magnetism become...

show abstract

Section: -3mentioning

confidence: 99%

Origin of the Spin-Orbital Liquid State in a NearlyJ=0IridateBa3ZnIr2O9

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…The kagomé antiferromagnets herbertsmithite and kapellasite have recently emerged as prominent examples [18][19][20][21][22][23][24] . The absence of magnetic order is evidenced by many different techniques including muon spin rotation and susceptibility measurements [18][19][20][21][22][23][24] , and neutron scattering measurements of herbertsmithite show a purely continuum spectrum, interpreted as a signature of fractional "spinon" excitations 23 . Further instances of QSLs have been found in organic Mott insulators with a triangular lattice structure [25][26][27] .…”

Section: Introductionmentioning

confidence: 99%

Global phase diagram of competing ordered and quantum spin-liquid phases on the kagome lattice

et al. 2015

View full text Add to dashboard Cite

We study the quantum phase diagram of the spin-1/2 Heisenberg model on the kagomé lattice with first-, second-, and third-neighbor interactions J1, J2, and J3 by means of density matrix renormalization group. For small J2 and J3, this model sustains a time-reversal invariant quantum spin liquid phase. With increasing J2 and J3, we find in addition a q = (0, 0) Néel phase, a chiral spin liquid phase, an apparent valence-bond crystal phase, and a complex non-coplanar magnetically ordered state with spins forming the vertices of a cuboctahedron known as a cuboc1 phase. Both the chiral spin liquid and cuboc1 phase break time reversal symmetry in the sense of spontaneous scalar spin chirality. We show that the chiralities in the chiral spin liquid and cuboc1 are distinct, and that these two states are separated by a strong first order phase transition. The transitions from the chiral spin liquid to both the q = (0, 0) phase and to time-reversal symmetric spin liquid, however, are consistent with continuous quantum phase transitions.

show abstract

“…Along with theoretical developments, experiments also discover different promising SL candidates in the triangular organic compounds [52][53][54] and kagome antiferromagnets Herbertsmithite and Kapellasite Cu 3 Zn(OH) 6 Cl 2 in recent years [55][56][57][58][59][60] . These materials appear to have gapless excitations as revealed by the specific heat and neutron scattering measurements [56][57][58][59] .…”

Section: Introductionmentioning

confidence: 99%

Chiral and critical spin liquids in a spin-12kagome antiferromagnet

2015

View full text Add to dashboard Cite

The kagome spin-1/2 systems have attracted intensive attentions in recent years as the primary candidate for hosting different gapped spin liquids (SL). To uncover the nature of the novel quantum phase transition between the SL states, we study a minimum XY model with the nearest neighbor (NN) (Jxy), the second and third NN couplings (J2xy = J3xy = J ′ xy ). We identify the time reversal symmetry broken chiral SL (CSL) with the turn on of a small perturbation J ′ xy ∼ 0.06Jxy, which is fully characterized by the fractionally quantized topological Chern number and the conformal edge spectrum as the ν = 1/2 fractional quantum Hall state. Interestingly, the NN XY model (J ′ xy = 0) is shown to be a critical SL state adjacent to the CSL, characterized by the gapless spin singlet and spin triplet excitations. The quantum phase transition from the CSL to the gapless critical SL is driven by the collapsing of the neutral (spin singlet) excitation gap. The effect of the NN spin-z coupling Jz is also studied, which leads to a quantum phase diagram with an extended regime for the gapless SL.

show abstract

Gapless Spin Liquid Ground State in theS=1/2Vanadium Oxyfluoride Kagome Antiferromagnet[NH4]2

Cited by 128 publications

References 36 publications

Origin of the Spin-Orbital Liquid State in a NearlyJ=0IridateBa3ZnIr2O9

Origin of the Spin-Orbital Liquid State in a NearlyJ=0IridateBa3ZnIr2O9

Global phase diagram of competing ordered and quantum spin-liquid phases on the kagome lattice

Chiral and critical spin liquids in a spin-12kagome antiferromagnet

Contact Info

Product

Resources

About