Related papers: Elementary excitations in undoped layered cuprates
We use recently proposed four-spin bond-operator technique (BOT) to discuss spectral properties of frustrated spin-$\frac12$ $J_1$--$J_2$ Heisenberg antiferromagnet on square lattice at $J_2<0.4J_1$ (i.e., in the N\'eel ordered phase). This…
We discuss spin-$\frac12$ Heisenberg antiferromagnet on the triangular lattice using the recently proposed bond-operator technique (BOT). We use the variant of the BOT which takes into account all spin degrees of freedom in the magnetic…
We present a bond-operator theory (BOT) suitable for description both magnetically ordered phases and paramagnetic phases with singlet ground states in spin-1/2 magnets. Proposed BOT provides a regular expansion of physical quantities in…
We theoretically discuss dynamical properties of spin-1/2 Heisenberg antiferromagnet on the triangular lattice in magnetic field $\bf H$. We use the recently proposed bond-operator theory which operates with quantum states of the whole…
Elementary excitations in condensed matter capture the complex many-body dynamics of interacting basic entities in a simple quasiparticle picture. In magnetic systems the most established quasiparticles are magnons, collective excitations…
Interactions between elementary excitations in quasi-one dimensional antiferromagnets are of experimental relevance and their quantitative theoretical treatment has been a theoretical challenge for many years. Using matrix product states,…
Understanding exotic forms of magnetism in quantum spin systems is an emergent topic of modern condensed matter physics. Quantum dynamics can be described by particle-like carriers of information, known-as quasiparticles that appear from…
Assemblies of interacting quantum particles often surprise us with properties that are difficult to predict. One of the simplest quantum many-body systems is the spin 1/2 Heisenberg antiferromagnetic chain, a linear array of interacting…
With the commutation relations of the spin operators, we first write out the equations of motion of the spin susceptibility and related correlation functions that have a hierarchical structure, then under the "soft cut-off" approximation,…
The elementary excitations of a model Hamiltonian that captures the low energy behavior of a simple two-fold degenerate Hubbard Hamiltonian with Hund's rule coupling, is studied. The phase diagram in the mean-field limit and in a two-site…
We study elementary excitations of spin-1 bosons with antiferromagnetic interaction in an optical lattice by applying the Gutzwiller approximation to the spin-1 Bose-Hubbard model. There appear various excitations associated with spin…
We discuss spin-$\frac12$ $J_1$--$J_2$ 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…
We study the dynamic spin structure factor of the spin-$1/2$ square-lattice Heisenberg antiferromagnet and of the $J$-$Q$ model (with 4-spin interactions $Q$ and Heisenberg exchange $J$). Using an improved method for stochastic analytic…
The square-lattice quantum Heisenberg antiferromagnet displays a pronounced anomaly of unknown origin in its magnetic excitation spectrum. The anomaly manifests itself only for short wavelength excitations propagating along the direction…
We numerically investigate elementary excitations of the Heisenberg alternating-spin chains with two kinds of spins 1 and 1/2 antiferromagnetically coupled to each other. Employing a recently developed efficient Monte Carlo technique as…
Correlation effects in CuO$_2$ layers give rise to a complicated landscape of collective excitations in high-T$_{\rm c}$ cuprates. Their description requires an accurate account for electronic fluctuations at a very broad energy range and…
Spin-only descriptions of the half-filled one-band Hubbard model are relevant for a wide range of Mott insulators. In addition to the usual Heisenberg exchange, many new types of interactions, including ring exchange, appear in the…
The exact elementary excitations in a typical U(1) symmetry broken quantum integrable system, that is the twisted J1-J2 spin chain with nearest-neighbor, next nearest neighbor and chiral three spin interactions, are studied. The main…
A unified theory for the cuprates and the iron-based superconductors is derived on the basis of common features in their electronic structures including quasi-two-dimensionality, and the large-U nature of the electron orbitals close to E_F…
We discuss spin-$\frac12$ two-dimensional (2D) Heisenberg antiferromagnet (AF) on a square lattice at T=0 in strong magnetic field H near its saturation value $H_c$. A perturbation approach is proposed to obtain spectrum of magnons with…