On the complexity of spinels: Magnetic, electronic, and polar ground states

Tsurkan, V.; Nidda, Hans‐Albrecht Krug von; Deisenhofer, J.; Lunkenheimer, P.; Loidl, A.

doi:10.1016/j.physrep.2021.04.002

Cited by 108 publications

(58 citation statements)

References 415 publications

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“…Quite interestingly, from these values an averaged magnetic moment of order 2.24 μ B can be calculated, corresponding exactly to the high-temperature value of a spin-orbit coupled (dε) 5 system, which is of order √ 5 ∼ = 2.24 [41]. The anisotropic magnetic moments are in reasonable agreement with PM moments published by other groups [16,17].…”

Section: Magnetic Susceptibility and Magnetizationsupporting

confidence: 83%

“…Notably, localized magnetic moments on a honeycomb lattice are realized in several iridate oxides. Moreover, their Ir 4+ ions with 5d 5 electron configuration exhibit strong spin-orbit coupling (SOC), which is believed to help promote the bonddependent interactions giving rise to a Kitaev QSL. Thus, these materials with an effective J eff = 1/2 ground state were identified as possible solid-state realizations of the Kitaev model [8,9].…”

Section: Introduction: Frustrated Magnets and Spin Liquidsmentioning

confidence: 99%

“…Subsequently, α-RuCl 3 came into the focus of solid-state research as a possible Kitaev spin-liquid candidate despite significantly smaller SOC [13][14][15][16][17][18][19]. In this compound, localized effective magnetic moments resulting from the Ru 3+ spins with a 4d 5 electron configuration are located on a honeycomb lattice and reveal only intermediate SOC, but again exhibit a J eff = 1/2 ground state.…”

Section: Introduction: Frustrated Magnets and Spin Liquidsmentioning

confidence: 99%

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On the proximate Kitaev quantum-spin liquid α-RuCl₃: thermodynamics, excitations and continua

Loidl

Lunkenheimer

Tsurkan

2021

J. Phys.: Condens. Matter

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This topical review provides an overview over recent thermodynamic, infrared, and THz results on the proximate Kitaev spin-liquid. Quantum-spin liquids are exotic phases characterized by the absence of magnetic ordering even at the lowest temperatures and by the occurrence of fractionalized spin excitations. Among those, Kitaev spin liquids are most fascinating as they belong to the rare class of model systems, that can be solved analytically by decomposing localized spins S = 1/2 into Majorana fermions. The main aim of this review is to summarize experimental evidence obtained by THz spectroscopy and utilizing heat-capacity experiments, which point to the existence of fractionalized excitations in the spin-liquid state, which in α-RuCl3 exists at temperatures just above the onset of magnetic order or at in-plane magnetic fields just beyond the quantum-critical point where antiferromagnetic order becomes suppressed. Thermodynamic and spectroscopic results are compared to theoretical predictions and model calculations. In addition, we document recent progress in elucidating the sub-gap (<1 eV) electronic structure of the 4d 5 ruthenium electrons to characterize their local electronic configuration. The on-site excitation spectra of the d electrons below the optical gap can be consistently explained using a spin–orbit coupling constant of ∼170 meV and the concept of multiple spin–orbital excitations. Furthermore, we discuss the phonon spectra of the title compound including rigid-plane shear and compression modes of the single molecular layers. In recent theoretical concepts it has been shown that phonons can couple to Majorana fermions and may play a substantial role in establishing the half-integer thermal quantum Hall effect observed in this material.

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Section: Magnetic Susceptibility and Magnetizationsupporting

confidence: 83%

Section: Introduction: Frustrated Magnets and Spin Liquidsmentioning

confidence: 99%

Section: Introduction: Frustrated Magnets and Spin Liquidsmentioning

confidence: 99%

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On the proximate Kitaev quantum-spin liquid α-RuCl₃: thermodynamics, excitations and continua

Loidl

Lunkenheimer

Tsurkan

2021

J. Phys.: Condens. Matter

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“…The AB 2 X 4 -type spinel compounds, with tetrahedral A-site and octahedral B-site, have been an anchoring point for some of the earliest work on magnetism that led to the seminal Néel [1] and the Yafet-Kittel models [2]. The spinel (and the inverse-spinel) compounds display a complex interplay among lattice, spin, charge, and orbital degrees of freedom [3], where novel phenomena emerge [4,5]. Indeed, interest in these systems persists as they exhibit exotic magnetic phenomena, such as multiferroic effects and the spin liquid state that result from spin-orbit coupling and geometric frustration associated with the pyrochlore sub-lattice of the B-site [6,7].…”

Section: Introductionmentioning

confidence: 99%

Localized-delocalized crossover of spin-carriers and magnetization reversal in Co$_{2}$VO$_{4}$

Kademane¹,

Bhandari²,

Paudyal³

et al. 2021

Preprint

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Neutron diffraction, magnetization and muon spin relaxation measurements, supplemented by density functional theory (DFT) calculations are employed to unravel temperature-driven magnetization reversal (MR) in inverse spinel Co2VO4. All measurements show a second order magnetic phase transition at TC = 168 K to a collinear ferrimagnetic phase. The DFT results suggest the moments in the ferrimagnetic phase are delocalized and undergo gradual localization as the temperature is lowered below TC. The delocalized-localized crossover gives rise to a maximum magnetization at TNC = 138 K and the continuous decrease in magnetization produces sign-change at TMR ∼ 65 K. Muon spectroscopy results support the DFT, as a strong T1-relaxation is observed around TNC, indicating highly delocalized spin-carriers gradually tend to localization upon cooling. The magnetization reversal determined at zero field is found to be highly sensitive to applied magnetic field, such that above B ∼ 0.25 T instead of a reversal a broad minimum in the magnetization is apparent at TMR. Analysis of the neutron diffraction measurements shows two antiparallel magnetic sublattice-structure, each belonging to magnetic ions on two distinct crystal lattice sites. The relative balance of these two structural components in essence determines the magnetization. Indeed, the order parameter of the magnetic phase on one site develops moderately more than that on the other site. Unusual tipping of the magnetic balance, caused by such site-specific magnetic fluctuation, gives rise to a spontaneous flipping of the magnetization as the temperature is lowered. * A.B.K and C.B contributed equally.[1] M. Néel, Propriétés magnétiques des ferrites ; ferrimagnétisme et antiferromagnétisme, Annales De Physique 12, 137 (1948). [2] Y. Yafet and C. Kittel, Antiferromagnetic arrangements in ferrites, Physical Review 87, 290 (1952).

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“…Above the threshold of |J 2 /J 1 | = 1/6, the ferromagnetic (FM, J 1 < 0) or Néel (J 1 > 0) state with q = 0 is replaced by a SSL state with nonzero q, and the spiral ring gradually transforms from a circular shape around the Brillouin zone center, Γ, into triangular lobes centered on the K { 1 3 , 1 3 } points as |J 2 /J 1 | increases. In spite of the elegant simplicity of the theoretical model, experimental realization of a SSL is challenging as J 2 is often relatively weak in real materials [18,[23][24][25][26][27][28][29]. To our knowledge, MnSc 2 S 4 has remained as the only host of a SSL on the diamond lattice [18], while the feasibility of realizing a SSL on the honeycomb lattice is still unclear.…”

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confidence: 99%

Spiral spin-liquid on a honeycomb lattice

Gao,

McGuire,

Liu

et al. 2021

Preprint

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Spiral spin-liquids are correlated paramagnetic states with degenerate propagation vectors forming a continuous ring or surface in reciprocal space. On the honeycomb lattice, spiral spin-liquids present a novel route to realize quantum spin liquids and topological spin textures, although their experimental realization remains elusive. Here, using neutron scattering, we show that a spiral spinliquid is realized in the van der Waals honeycomb magnet FeCl3. A continuous ring of scattering in reciprocal space is directly observed, and the intensity distribution is accurately described by a Heisenberg model with competing exchange interactions. Our work demonstrates that spiral spinliquids can be realized in two-dimensional systems and represents a crucial step in the quest for quantum spin liquids and topological spin textures on the honeycomb lattice.

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On the complexity of spinels: Magnetic, electronic, and polar ground states

Cited by 108 publications

References 415 publications

On the proximate Kitaev quantum-spin liquid α-RuCl₃: thermodynamics, excitations and continua

On the proximate Kitaev quantum-spin liquid α-RuCl₃: thermodynamics, excitations and continua

Localized-delocalized crossover of spin-carriers and magnetization reversal in Co$_{2}$VO$_{4}$

Spiral spin-liquid on a honeycomb lattice

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On the complexity of spinels: Magnetic, electronic, and polar ground states

Cited by 108 publications

References 415 publications

On the proximate Kitaev quantum-spin liquid α-RuCl3: thermodynamics, excitations and continua

On the proximate Kitaev quantum-spin liquid α-RuCl3: thermodynamics, excitations and continua

Localized-delocalized crossover of spin-carriers and magnetization reversal in Co$_{2}$VO$_{4}$

Spiral spin-liquid on a honeycomb lattice

Contact Info

Product

Resources

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On the proximate Kitaev quantum-spin liquid α-RuCl₃: thermodynamics, excitations and continua

On the proximate Kitaev quantum-spin liquid α-RuCl₃: thermodynamics, excitations and continua