Thermodynamic evidence of fractionalized excitations in α-RuCl3

Abstract

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-RuCl3 and undertook considerable efforts to determine the exact phonon background. We measured single-crystalline RhCl3 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 RhCl3 with its minute difference from the title compound. In α-RuCl3 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.

References in corpus (41)

• Anyons in an exactly solved model and beyond
• Majorana quantization and half-integer thermal quantum Hall effect in a Kitaev spin liquid
• Proximate Kitaev Quantum Spin Liquid Behaviour in α-RuCl${}_3$
• Models and Materials for Generalized Kitaev Magnetism
• The monoclinic crystal structure of $\alpha$-RuCl${}_3$ and the zigzag antiferromagnetic ground state
• Scattering Continuum and Possible Fractionalized Excitations in $\alpha$-RuCl${}_3$
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections
• Low-temperature crystal and magnetic structure of $\alpha$-RuCl3
• Evidence for a Field-induced Quantum Spin Liquid in $\alpha$-RuCl${}_3$
• Excitations in the field-induced quantum spin liquid state of alpha-RuCl3
• Successive magnetic phase transitions in $\mathbf{\alpha }$-RuCl${}_3$: XY-like frustrated magnet on the honeycomb lattice
• Kitaev magnetism in honeycomb RuCl3 with intermediate spin-orbit coupling
• Fermionic response from fractionalization in an insulating two-dimensional magnet
• Breakdown of Magnons in a Strongly Spin-Orbital Coupled Magnet
• Phase Diagram of $\alpha$-RuCl${}_3$ in an in-plane Magnetic Field
• Thermal fractionalization of quantum spins in a Kitaev model: $T$-linear specific heat and coherent transport of Majorana fermions
• Gapless Spin Excitations in the Field-Induced Quantum Spin Liquid Phase of alpha-RuCl3
• Spin-wave excitations evidencing the Kitaev interaction in single crystalline $\alpha$-RuCl${}_3$
• Anisotropic Ru3+ 4d5 magnetism in the alpha-RuCl3 honeycomb system: susceptibility, specific heat and Zero field NMR
• Vaporization of Kitaev spin liquids
• Field-induced quantum criticality in the Kitaev system $\alpha$-RuCl${}_3$
• Magnetic Excitations and Continuum of a Field-Induced Quantum Spin Liquid in $\alpha$-RuCl${}_3$
• Magnetization processes of zigzag states on the honeycomb lattice: Identifying spin models for $\alpha$-RuCl${}_3$ and Na${}_2$IrO${}_3$
• Probing $\alpha$-RuCl${}_3$ Beyond Magnetic Order: Effects of Temperature and Magnetic Field
• Relation between Kitaev magnetism and structure in $\alpha$-RuCl${}_3$
• Characteristic Crossing Points in Specific Heat Curves of Correlated Systems
• Fractional Spin Fluctuation as a Precursor of Quantum Spin Liquids: Majorana Dynamical Mean-Field Study for the Kitaev Model
• Clues and criteria for designing Kitaev spin liquid revealed by thermal and spin excitations of honeycomb iridates Na${}_2$IrO${}_3$
• Antiferromagnetic resonance and terahertz continuum in $\alpha -$RuCl${}_3$
• Magnetic thermal conductivity far above the Néel temperatures in the Kitaev-magnet candidate $\alpha$-RuCl${}_3$
• Path to stable quantum spin liquids in spin-orbit coupled correlated materials
• Quantum spin liquid at finite temperature: proximate dynamics and persistent typicality
• Classical and quantum spin dynamics of the honeycomb $\Gamma$ model
• Detuning the Honeycomb of $\alpha$-RuCl${}_3$: Pressure-Dependent Optical Studies Reveal Broken Symmetry
• Electronic and phonon excitations in α-RuCl${}_3$
• High-temperature magnetostructural transition in van der Waals-layered a-MoCl3
• Effective model with strong Kitaev interactions for $\alpha$-$\mathrm{RuC}{\mathrm{l}}_3$
• Heat transport in the anisotropic Kitaev spin liquid
• Uniaxial and hydrostatic pressure effects in alpha-RuCl3 single crystals via thermal-expansion measurements
• Sub-gap optical response across the structural phase transition in van der Waals layered α-RuCl${}_3$

Cited by in corpus (56)

• Half-integer quantized anomalous thermal Hall effect in the Kitaev material $\alpha$-RuCl${}_3$
• Hunting Majorana Fermions in Kitaev Magnets
• Dynamical and thermal magnetic properties of the Kitaev spin liquid candidate $\alpha$-RuCl${}_3$
• High-Field Quantum Disordered State in $\alpha$-RuCl3: Spin Flips, Bound States, and a Multi-Particle Continuum
• Identification of Magnetic Interactions and High-field Quantum Spin Liquid in $\alpha$-RuCl${}_3$
• Unusual heat transport of the Kitaev material Na${}_2$Co${}_2$TeO${}_6$: putative quantum spin liquid and low-energy spin excitations
• Thermal Hall effects in quantum magnets
• Thermodynamic and Transport Properties in Disordered Kitaev Models
• Electrical probes of the non-Abelian spin liquid in Kitaev materials
• The Heart of Entanglement: Chiral, Nematic, and Incommensurate Phases in the Kitaev-Gamma Ladder in a Field
• Phonon renormalization in the Kitaev quantum spin liquid
• Giant Phonon Anomalies in the Proximate Kitaev Quantum Spin Liquid $\alpha$-RuCl${}_3$
• Electronic and magnetic properties of the RuX${}_3$ (X=Cl, Br, I) family: Two siblings -- and a cousin?
• Field-induced phase transitions of the Kitaev material $\alpha$-RuCl${}_3$ probed by thermal expansion and magnetostriction
• Disorder upon disorder: localization effects in the Kitaev spin liquid
• Majorana-fermion origin of the planar thermal Hall effect in the Kitaev magnet $\alpha$-RuCl${}_3$
• Effect of structural disorder on the Kitaev magnet Ag${}_3$LiIr${}_2$O${}_6$
• Spin-glass state and reversed magnetic anisotropy induced by Cr doping in the Kitaev magnet $\alpha$-RuCl${}_3$
• Kitaev Quantum Spin Liquids
• Universal Thermodynamics in the Kitaev Fractional Liquid
• THz excitations in α-RuCl3: Majorana fermions, rigid-plane shear and compression modes
• Extraction of the interaction parameters for $\alpha -$RuCl${}_3$ from neutron data using machine learning
• Stacking faults in $\alpha$-RuCl${}_3$ revealed by local electric polarization
• Evidence for the first-order topological phase transition in a Kitaev spin liquid candidate $\alpha$-RuCl${}_3$
• Toward cubic symmetry for Ir${}^{4+}$: structure and magnetism of antifluorite K${}_2$IrBr${}_6$
• Thermal anyon interferometry in phonon-coupled Kitaev spin liquids
• Flux mobility delocalization in the Kitaev spin ladder
• Defect-Induced Low-Energy Majorana Excitations in the Kitaev Magnet $\alpha$-RuCl${}_3$
• Learning Effective Spin Hamiltonian of Quantum Magnet
• Proximate Kitaev system for an intermediate magnetic phase in in-plane magnetic fields
• Acoustic phonon dispersion of $\alpha$-RuCl${}_3$
• Two-step growth of high-quality single crystals of the Kitaev magnet $\alpha$-RuCl${}_3$
• Neutron spectroscopy evidence for a possible magnetic-field-induced gapless quantum-spin-liquid phase in a Kitaev material $\alpha$-RuCl${}_3$
• Thermodynamic evidence for field-angle dependent Majorana gap in a Kitaev spin liquid
• Weak-coupling to strong-coupling quantum criticality crossover in a Kitaev quantum spin liquid $\alpha$-RuCl${}_3$
• Magnetothermal transport in ultraclean single crystals of Kitaev magnet $\alpha$-RuCl${}_3$
• Static and fluctuating zigzag order, and possible signatures of Kitaev physics, in torque measurements of $\alpha$-RuCl${}_3$
• Ultrafast spin dynamics in the proximate quantum spin liquid α-RuCl3
• High-field quantum spin liquid transitions and angle-field phase diagram of Kitaev magnet $\alpha$-RuCl${}_3$
• Dilution of the magnetic lattice in the Kitaev candidate $\alpha$-RuCl${}_3$ by Rh${}^{3+}$ doping
• Evidence for distortion-induced local electric polarization in $\alpha$-RuCl${}_3$
• Ground state and magnetic transitions of the orthorhombic antiferromagnet CaCo${}_2$TeO${}_6$
• Intermediate phases in $\alpha$-RuCl${}_3$ under in-plane magnetic field via interlayer spin interactions
• Bulk excitations in ultraclean $\alpha$-RuCl${}_3$: Quantitative evidence for Majorana dispersions in a Kitaev quantum spin liquid
• Real-time control of non-Abelian anyons in Kitaev spin liquid under energy dissipation
• Field tuning Kitaev systems for spin fractionalization and topological order
• Coupled spin-1/2 antiferromagnetic chain Cs${}_2$LiRuCl${}_6$ with partially disordered crystal lattice
• A primer on Kitaev Model: Basic aspects, material realization, and recent experiments
• High temperature antiferromagnetism in ultrathin SrRu2O6 nanosheets
• Thermodynamic behavior of modified integer-spin Kitaev models on the honeycomb lattice
• Robustness of Vacancy-Bound Non-Abelian Anyons in the Kitaev Model in a Magnetic Field
• Real-space spectral simulation of quantum spin models: Application to generalized Kitaev models
• The field-angle anisotropy of proximate Kitaev systems under an in-plane magnetic field
• Signatures of a Majorana-Fermi surface in the Kitaev magnet Ag${}_3$LiIr${}_2$O${}_6$
• Critical behavior and evidence of dimensional crossover in quasi-two-dimensional Li${}_2$FeSiO${}_4$
• The Role of the Third Dimension in Searching Majorana Fermions in $\alpha$-RuCl${}_3$ via Phonons