Magnetic Excitations and Continuum of a Possibly Field-Induced Quantum Spin Liquid in 
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Wang, Zhe; Reschke, S.; Hüvonen, D.; Do, Seung-Hwan; Choi, Kwang‐Yong; Gensch, Michael; Nagel, U.; Rõõm, T.; Loidl, A.

doi:10.1103/physrevlett.119.227202

Cited by 191 publications

(198 citation statements)

References 53 publications

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“…Consistent with the hypothesis of a magnetic origin of these resonances, we note that mode II was recently observed in independent TDTS [31][32][33]56] and EPR [34] experiments and assigned to a zone-center magnon of the zigzag ordered phase. On the other hand, while signatures of mode I have also been seen in previous measurements [28,31], this resonance has never been discussed.…”

Section: B Assignment Of the Resonancessupporting

confidence: 90%

“…1(b)] [23,24]. Nevertheless, spectroscopic probes, including inelastic neutron scattering (INS) [25][26][27][28], spontaneous Raman scattering [29,30], time-domain terahertz spectroscopy (TDTS) [31][32][33], and electron paramagnetic resonance (EPR) [34], have discovered signatures of a field-induced QSL state above 7.5 T in the form of a broad continuum at the 2D magnetic Brillouin zone center. Yet a complete understanding of the origin of these excitations as well as of the spin dynamics is still lacking.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic field-dependent low-energy magnon dynamics in α–RuCl3

et al. 2019

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Revealing the spin excitations of complex quantum magnets is key to developing a minimal model that explains the underlying magnetic correlations in the ground state. We investigate the lowenergy magnons in α-RuCl3 by combining time-domain terahertz spectroscopy under an external magnetic field and model Hamiltonian calculations. We observe two absorption peaks around 2.0 and 2.4 meV, which we attribute to zone-center spin waves. Using linear spin-wave theory with only nearest-neighbor terms of the exchange couplings, we calculate the antiferromagnetic resonance frequencies and reveal their dependence on an external field applied parallel to the nearest-neighbor Ru-Ru bonds. We find that the magnon behavior in an applied magnetic field can be understood only by including an off-diagonal Γ exchange term to the minimal Heisenberg-Kitaev model. Such an anisotropic exchange interaction that manifests itself as a result of strong spin-orbit coupling can naturally account for the observed mixing of the modes at higher fields strengths. arXiv:1909.00462v1 [cond-mat.str-el] 1 Sep 2019

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Section: B Assignment Of the Resonancessupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Magnetic field-dependent low-energy magnon dynamics in α–RuCl3

et al. 2019

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“…The sudden change in the spectrum is consistent with a value for B u between 8.5 T and 9 T. The peak energy increases roughly linearly with field in region III, and in the overlap region agrees with the gap energy extracted from thermal conductivity measurements [39]. The slope of the mode energies in the high field regime above B u is consistent with the results of other techniques [17,18,22]. As seen in figure 2(b), in region III the bandwidth increases with increasing field.…”

Section: Range [Mev] Range [Mev] Counts Countssupporting

confidence: 88%

Finite field regime for a quantum spin liquid in α−RuCl3

et al. 2019

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An external magnetic field can induce a transition in α-RuCl3 from an ordered zigzag state to a disordered state that is possibly related to the Kitaev quantum spin liquid. Here we present new field dependent inelastic neutron scattering and magnetocaloric effect measurements implying the existence of an additional transition out of the quantum spin liquid phase at an upper field limit Bu. The neutron scattering shows three distinct regimes of magnetic response. In the low field ordered state the response shows magnon peaks; the intermediate field regime shows only continuum scattering, and above Bu the response shows sharp magnon peaks at the lower bound of a strong continuum. Measurable dispersion of magnon modes along the (0, 0, L) direction implies non-negligible inter-plane interactions. Combining the magnetocaloric effect measurements with other data a T − B phase diagram is constructed. The results constrain the range where one might expect to observe quantum spin liquid behavior in α-RuCl3. arXiv:1903.00056v3 [cond-mat.str-el]

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“…Utilizing a model with ferromagnetic Kitaev and antiferromagnetic symmetric off-diagonal exchange , Catuneanu et al [9] and Samarakoon et al [10] calculated susceptibilities and thermodynamic quantities of the Kitaev spin-liquid candidate α-RuCl3. The main motivation was to explain the scattering continua as observed by neutron [11,12,13,14] and Raman scattering experiments [15,16,17] as well as by THz spectroscopy [18,19], but these authors also calculated the temperature dependence of heat capacity and found the characteristic two-peak structure and the concomitant twostep evolution of entropy. With the characteristic exchange parameters of K and  of the title compound, according to these authors, the two peaks in the heat capacity are located close to 0.03  and 0.4 .…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic evidence of fractionalized excitations in α−RuCl3

et al. 2019

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Fractionalized excitations are of considerable interest in recent condensed-matter physics. Fractionalization of the spin degrees of freedom into localized and itinerant Majorana fermions are predicted for the Kitaev spin liquid, an exactly solvable model with bond-dependent interactions on a two-dimensional honeycomb lattice. As function of temperature, theory predicts a characteristic two-peak structure of the heat capacity as fingerprint of these excitations. Here we report on detailed heat-capacity experiments as function of temperature and magnetic field in high-quality single crystals of α-RuCl 3 and undertook considerable efforts to determine the exact phonon background. We measured single-crystalline RhCl 3 as non-magnetic reference and performed ab-initio calculations of the phonon density of states for both compounds. These ab-initio calculations document that the intrinsic phonon contribution to the heat capacity cannot be obtained by a simple rescaling of the nonmagnetic reference using differences in the atomic masses. Sizable renormalization is required even for non-magnetic RhCl 3 with its minute difference from the title compound. In α-RuCl 3 in zero magnetic field, excess heat capacity exists at temperatures well above the onset of magnetic order. In external magnetic fields far beyond quantum criticality, when long-range magnetic order is fully suppressed, the excess heat capacity exhibits the characteristic two-peak structure. In zero field, the lower peak just appears at temperatures around the onset of magnetic order and seems to be connected with canonical spin degrees of freedom. At higher fields, beyond the critical field, this peak is shifted to 10 K. The high-temperature peak located around 50 K is hardly influenced by external magnetic fields, carries the predicted amount of entropy, R/2 ln2, and may resemble remnants of Kitaev physics.

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Magnetic Excitations and Continuum of a Possibly Field-Induced Quantum Spin Liquid in α−RuCl3

Cited by 191 publications

References 53 publications

Magnetic field-dependent low-energy magnon dynamics in α–RuCl3

Magnetic field-dependent low-energy magnon dynamics in α–RuCl3

Finite field regime for a quantum spin liquid in α−RuCl3

Thermodynamic evidence of fractionalized excitations in α−RuCl3

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