Disorder-induced excitation continuum in a spin-1/2 cobaltate on a triangular lattice

Abstract

A spin-1/2 triangular-lattice antiferromagnet is a prototypical frustrated quantum magnet, which exhibits remarkable quantum many-body effects that arise from the synergy between geometric spin frustration and quantum fluctuations. It can host quantum frustrated magnetic topological phenomena like quantum spin liquid (QSL) states, highlighted by the presence of fractionalized quasiparticles within a continuum of magnetic excitations. In this work, we use neutron scattering to study CoZnMo${}_3$O${}_8$, which has a triangular lattice of Jeff = 1/2 Co2+ ions with octahedral coordination. We found a wave-vector-dependent excitation continuum at low energy that disappears with increasing temperature. Although these excitations are reminiscent of a spin excitation continuum in a QSL state, their presence in CoZnMo${}_3$O${}_8$ originates from magnetic intersite disorder-induced dynamic spin states with peculiar excitations. Our results, therefore, give direct experimental evidence for the presence of a disorder-induced spin excitation continuum.

References in corpus (12)

• Continuous excitations of the triangular-lattice quantum spin liquid YbMgGaO4
• Pseudospin exchange interactions in d^7 cobalt compounds: Possible realization of the Kitaev model
• Kitaev-Heisenberg Hamiltonian for High-Spin $d^7$ Mott Insulators
• Hidden symmetries of the extended Kitaev-Heisenberg model: Implications for honeycomb lattice iridates A2IrO3
• Weak-field induced nonmagnetic state in a Co-based honeycomb
• Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice
• Diagonal magnetoelectric susceptibility and effect of Fe-doping in a polar ferrimagnet Mn2Mo3O8
• Survival of itinerant excitations and quantum spin state transitions in YbMgGaO${}_4$ with chemical disorder
• Magnetic excitations of the field induced states in BaCo2(AsO4)2 probed by time-domain terahertz spectroscopy
• Effect of structural disorder on the Kitaev magnet Ag${}_3$LiIr${}_2$O${}_6$
• Picosecond creation of switchable optomagnets with giant photoinduced Kerr rotations in polar antiferromagnetic (Fe${}_{1-x}$Zn${}_x$)${}_2$Mo${}_3$O${}_8$
• Evidence for gapless quantum spin liquid in a honeycomb lattice