Evidence for a spinon Fermi surface in the triangular S=1 quantum spin liquid Ba${}_3$NiSb${}_2$O${}_9$

Abstract

Inelastic neutron scattering is used to study the low-energy magnetic excitations in the spin-1 triangular lattice of the 6H-B phase of Ba${}_3$NiSb${}_2$O${}_9$. We study two powder samples: Ba${}_3$NiSb${}_2$O${}_9$ synthesized under high pressure and Ba${}_{2.5}$Sr${}_{0.5}$NiSb${}_2$O${}_9$ in which chemical pressure stabilizes the 6H-B structure. The measured excitation spectra show broad gapless and nondispersive continua at characteristic wave vectors. Our data rules out most theoretical scenarios that have previously been proposed for this phase, and we find that it is well described by an exotic quantum spin liquid with three flavors of unpaired fermionic spinons, forming a large spinon Fermi surface.

4+9 pages, 4 figures; published version

References in corpus (10)

• Continuous excitations of the triangular-lattice quantum spin liquid YbMgGaO4
• Low energy effective theory of Fermi surface coupled with U(1) gauge field in 2+1 dimensions
• Properties of an algebraic spin liquid on the kagome lattice
• The quadrupolar phases of the S=1 bilinear-biquadratic Heisenberg model on the triangular lattice
• Fractional excitations in the square-lattice quantum antiferromagnet
• Time-reversal-symmetry-breaking chiral spin liquids: a projective symmetry group approach of bosonic mean-field theories
• Paired chiral spin liquid with a Fermi surface in S=1 model on the triangular lattice
• Fermionic theory for quantum antiferromagnets with spin S > 1/2
• Two-mode variational Monte Carlo study of Quasiparticle excitations in cuprates
• Quasiparticle spectral weights of Gutzwiller-projected high T_c superconductors

Cited by in corpus (2)

• A tensor network study of the complete ground state phase diagram of the spin-1 bilinear-biquadratic Heisenberg model on the square lattice
• Gapless chiral spin liquid from coupled chains on the kagome lattice