Weak-coupling to strong-coupling quantum criticality crossover in a Kitaev quantum spin liquid $\alpha$-RuCl${}_3$

Abstract

We report an unprecedented quantum criticality crossover representing two different universal scaling behaviors in a Kitaev quantum magnetic material $\alpha$-RuCl${}_3$. $\alpha$-RuCl${}_3$ presents both a symmetry breaking antiferromagnetic order and a long-range entangled topological order of a quantum spin liquid, and thus could be a candidate system for a new universality class involving deconfined fractionalized excitations of the local Z${}_2$ fluxes and itinerant Majorana fermions. Theoretical analyses on the inelastic neutron scattering and specific heat results demonstrate that Wilson-Fisher-Yukawa-type 'conventional' weak-coupling quantum criticality in high energy scales crosses over to heavy-fermion-type 'local' strong-coupling one in low energy scales. Our findings provide deep insight on how the quantum criticality evolves in fermion-boson coupled topological systems with different types of deconfined fermions.

14 pages, 11 figures

References in corpus (11)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Quantum criticality
• 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
• Quantum magnetism and criticality
• Spinons and triplons in spatially anisotropic frustrated antiferromagnets
• Edge solitons of topological insulators and fractionalized quasiparticles in two dimensions
• Theory of the field-revealed Kitaev spin liquid
• Origin of oscillatory structures in the magnetothermal conductivity of the putative Kitaev magnet $\alpha$-RuCl${}_3$

Cited by in corpus (4)

• Continuous spin excitations in the three-dimensional frustrated magnet K2Ni2(SO4)3
• Quantum phase transitions and composite excitations of antiferromagnetic spin trimer chains in a magnetic field
• Mott Gap Softening Coinciding with Spin Correlations Collapse in a-RuCl3
• Using magnetic dynamics to measure the spin gap in a candidate Kitaev material