We study the effects of a uniform magnetic field on the one-dimensional spin-orbital model in terms of effective field theories. Two regions are examined: one around the SU(4) point $(J=K/4)$ and the other with $K\ensuremath{\ll}J$ [see Eq. (1)]. We found that when $J<~K/4,$ the spin and orbital correlation functions exhibit power-law decay with nonuniversal exponents. In the region with $J>K/4,$ the excitation spectrum has a gap but the structure of it changes at different range of the ratio $J/K.$ Furthermore, near the SU(4) point, the magnetic field exerts a great influence on the spectrum of the ${S}^{z}=0$ sector. When the magnetic field is beyond some critical value, a quantum phase transition occurs. The different structure of the excitation spectrum results in distinct critical behavior of correlation functions around the SU(4) point and the region with $K\ensuremath{\ll}J.$ Especially, the exponents in the latter case are universal.We study the effects of a uniform magnetic field on the one-dimensional spin-orbital model in terms of effective field theories. Two regions are examined: one around the SU(4) point $(J=K/4)$ and the other with $K\ensuremath{\ll}J$ [see Eq. (1)]. We found that when $J<~K/4,$ the spin and orbital correlation functions exhibit power-law decay with nonuniversal exponents. In the region with $J>K/4,$ the excitation spectrum has a gap but the structure of it changes at different range of the ratio $J/K.$ Furthermore, near the SU(4) point, the magnetic field exerts a great influence on the spectrum of the ${S}^{z}=0$ sector. When the magnetic field is beyond some critical value, a quantum phase transition occurs. The different structure of the excitation spectrum results in distinct critical behavior of correlation functions around the SU(4) point and the region with $K\ensuremath{\ll}J.$ Especially, the exponents in the latter case are universal.

arXiv:cond-mat/9909394Physical review. B, Condensed matterMar 1, 20009 citations

Excitation spectrum of the one-dimensional Hubbard model

Cornelius F. Coll

Advanced series in mathematical physicsMay 1, 19942 citations

One-dimensionalXY model: Ergodic properties and hydrodynamic limit

A. G. Shuhov, Yu. M. Suhov

Journal of Statistical PhysicsNov 1, 19861 citation

Dynamical properties of spin-orbital chains in a magnetic field

Weiqiang Yu, Stephan Haas

The excitation spectrum of the one-dimensional spin-orbital model in a magnetic field is studied, using a recently developed dynamical density-matrix renormalization-group technique. The method is applied to chains with up to 80 sites, and examined for test cases such as the one-dimensional spin-1/2 Heisenberg antiferromagnet whose excitation spectrum is known exactly from the Bethe ansatz. In the spin-orbital chain, the characteristic dynamical response depends strongly on the model parameters and the applied magnetic field. The coupling between the spin and orbital degrees of freedom is found to influence the incommensuration at finite magnetizations. In the regions of the phase diagram with only massive spin and orbital excitations, a finite field is required to overcome the spin gap. An orbital mode is found to become massless in this partially spin-polarized regime, indicating a strong coupling between the two degrees of freedom. In the critical region with three elementary gapless excitations, a prominent particle-hole excitation is observed at higher energies, promoted by the biquadratic term in the model Hamiltonian of the spin-orbital chain.The excitation spectrum of the one-dimensional spin-orbital model in a magnetic field is studied, using a recently developed dynamical density-matrix renormalization-group technique. The method is applied to chains with up to 80 sites, and examined for test cases such as the one-dimensional spin-1/2 Heisenberg antiferromagnet whose excitation spectrum is known exactly from the Bethe ansatz. In the spin-orbital chain, the characteristic dynamical response depends strongly on the model parameters and the applied magnetic field. The coupling between the spin and orbital degrees of freedom is found to influence the incommensuration at finite magnetizations. In the regions of the phase diagram with only massive spin and orbital excitations, a finite field is required to overcome the spin gap. An orbital mode is found to become massless in this partially spin-polarized regime, indicating a strong coupling between the two degrees of freedom. In the critical region with three elementary gapless excitations, a prominent particle-hole excitation is observed at higher energies, promoted by the biquadratic term in the model Hamiltonian of the spin-orbital chain.

arXiv:cond-mat/0005526Physical review. B, Condensed matterDec 20, 200013 citations

We study the effects of a uniform magnetic field on the one-dimensional spin-orbital model in terms of effective field theories. Two regions are examined: one around the SU(4) point

(J=K/4)

and the other with $K\ensuremath{\ll}J$ [see Eq. (1)]. We found that when

J<~K/4,

the spin and orbital correlation functions exhibit power-law decay with nonuniversal exponents. In the region with

J>K/4,

the excitation spectrum has a gap but the structure of it changes at different range of the ratio

J/K.

Furthermore, near the SU(4) point, the magnetic field exerts a great influence on the spectrum of the

{S}^{z}=0

sector. When the magnetic field is beyond some critical value, a quantum phase transition occurs. The different structure of the excitation spectrum results in distinct critical behavior of correlation functions around the SU(4) point and the region with $K\ensuremath{\ll}J.$ Especially, the exponents in the latter case are universal.