Dynamics of spin-1/2 $J_1$-$J_2$ model on the triangular lattice

Abstract

We discuss spin-$\frac{1}{2}$ $J_1$--$J_2$ model on the triangular lattice using recently proposed bond-operator theory (BOT). In agreement with previous discussions of this system, we obtain four phases upon $J_2$ increasing: the phase with $120^{\circ }$ ordering of three sublattices, the spin-liquid phase, the state with the collinear stripe order, and the spiral phase. The $120^{\circ }$ and the stripe phases are discussed in detail. All calculated static characteristics of the model are in good agreement with previous numerical findings. In the $120^{\circ }$ phase, we observe the evolution of quasiparticles spectra and dynamical structure factors (DSFs) upon approaching the spin-liquid phase. Some of the considered elementary excitations were introduced first in our recent study of this system at $J_2=0$ using the BOT. In the stripe phase, we observe that the doubly degenerate magnon spectrum known from the spin-wave theory (SWT) is split by quantum fluctuations which are taken into account more accurately in the BOT. As compared with other known findings of the SWT in the stripe state, we observe additional spin-1 and spin-0 quasiparticles which give visible anomalies in the transverse and longitudinal DSFs. We obtain also a special spin-0 quasiparticle named singlon who produces a peak only in four-spin correlator and who is invisible in the longitudinal DSF. We show that the singlon spectrum lies below energies of all spin-0 and spin-1 excitations in some parts of the Brillouin zone. Singlon spectrum at zero momentum can be probed by the Raman scattering.

arXiv comment13 pages, 9 figures

References in corpus (19)

• Long range Neel order in the triangular Heisenberg model
• Exact spectra, spin susceptibilities and order parameter of the quantum Heisenberg antiferromagnet on the triangular lattice
• Spin liquid nature in the Heisenberg $J_1$-$J_2$ triangular antiferromagnet
• Spontaneous Magnon Decays
• Spin liquid phase of the $S=\frac{1}{2}$ $J_1-J_2$ Heisenberg model on the triangular lattice
• Spin-waves in triangular lattice antiferromagnet: decays, spectrum renormalization, and singularities
• Competing Spin Liquid States in the Spin-$1/2$ Heisenberg Model On Triangular Lattice
• Excitation spectra of the spin-1/2 triangular-lattice Heisenberg antiferromagnet
• Gapless spin-liquid phase in an extended spin 1/2 triangular Heisenberg model
• Static and Dynamical Properties of the Spin-1/2 Equilateral Triangular-Lattice Antiferromagnet Ba${}_3$CoSb${}_2$O${}_9$
• Flat spin wave dispersion in a triangular antiferromagnet
• Dynamical structure factor of the $J_1-J_2$ Heisenberg model on the triangular lattice: magnons, spinons, and gauge fields
• Quasiclassical magnetic order and its loss in a spin-1/2 Heisenberg antiferromagnet on a triangular lattice with competing bonds
• Avoided quasiparticle decay and enhanced excitation continuum in the spin-1/2 near-Heisenberg triangular antiferromagnet Ba3CoSb2O9
• Evidence of Two-Spinon Bound States in the Magnetic Spectrum of Ba${}_3$CoSb${}_2$O${}_9$
• Elementary excitations in the ordered phase of spin-1/2 J1-J2 model on square lattice
• Novel elementary excitations in spin-1/2 antiferromagnets on the triangular lattice
• Collective excitations in spin-1/2 magnets through bond-operator formalism designed both for paramagnetic and ordered phases
• Multiple magnon modes in spin-1/2 Heisenberg antiferromagnet on simple square lattice in strong magnetic field

Cited by in corpus (2)

• Superconductivity in doped triangular Mott insulators: the roles of parent spin backgrounds and charge kinetic energy
• Elementary excitations in undoped layered cuprates