Kavli Affiliate: Leon Balents
| First 5 Authors: Bin Gao, Tong Chen, Chunxiao Liu, Mason L. Klemm, Shu Zhang
| Summary:
In magnetically ordered insulators, elementary quasiparticles manifest as
spin waves – collective motions of localized magnetic moments propagating
through the lattice – observed via inelastic neutron scattering. In effective
spin-1/2 systems where geometric frustrations suppress static magnetic order,
spin excitation continua can emerge, either from degenerate classical spin
ground states or from entangled quantum spins characterized by emergent gauge
fields and deconfined fractionalized excitations. Comparing the spin
Hamiltonian with theoretical models can unveil the microscopic origins of these
zero-field spin excitation continua. Here, we use neutron scattering to study
spin excitations of the two-dimensional (2D) triangular-lattice effective
spin-1/2 antiferromagnet CeMgAl11O19. Analyzing the spin waves in the
field-polarized ferromagnetic state, we find that the spin Hamiltonian is close
to an exactly solvable 2D triangular-lattice XXZ model, where degenerate
120$^circ$ ordered ground states – umbrella states – develop in the zero
temperature limit. We then find that the observed zero-field spin excitation
continuum matches the calculated ensemble of spin waves from the umbrella state
manifold, and thus conclude that CeMgAl11O19 is the first example of an exactly
solvable spin liquid on a triangular lattice where the spin excitation
continuum arises from the ground state degeneracy.
| Search Query: ArXiv Query: search_query=au:”Leon Balents”&id_list=&start=0&max_results=3