Spin-charge coupling in correlated one-dimensional quantum systems

Hiroaki Matsueda, Takami Tohyama, Sadamichi Maekawa

Norikazu Tomita, Keiichirō Nasu

We study fluctuation effects of nonlinear coupling between spin and charge excitations on dynamical correlation functions of the one-dimensional extended Hubbard model at half-filling. Two kinds of dynamical correlation functions, dynamical spin- and charge-correlation functions, are calculated by means of a quantum Monte Carlo simulation. We show that the dynamical spin-correlation function has a new peak on the high-energy side of the well-known magnon peak. Since this peak always appears above the charge-excitation gap, it should originate from a charge fluctuation induced through a final-state interaction of magnon creation. We also show that in the dynamical charge-correlation function, a charge-transfer excitation peak is broadened by fluctuation effects due to magnons. These results clearly show that spin and charge excitations are nonlinearly coupled in this system.

Nelson Oyindenyifa Nenuwe

Anı́bal Iucci

We compute correlation functions for one-dimensional electron systems in which spin and charge degrees of freedom are coupled through spin-orbit coupling. Charge density waves, spin density waves, and singlet- and triplet-superconducting fluctuations are studied. We show that the spin-orbit interaction modifies the exponents and the phase diagram of the system, changing the dominant fluctuations and making new susceptibilities diverge for low temperature.

C. A. Balseiro, E. A. Jagla, K. Hallberg

Akira Takahashi, Hiroki Gomi, Masaki Aihara

We theoretically investigate the dynamics of photoexcited states in strongly correlated low-dimensional electron systems by analyzing the transient four-wave mixing (TFWM). We adopt the effective Hamiltonian of the Hubbard model for the photoexcited states in the strong correlation case, and TFWM intensity is obtained by numerically calculating the time development of the photoexcited state. We find that TFWM intensity sensitively reflects the relaxation due to the diffusion of the photogenerated charges and the relaxation due to the spin structure rearrangement to the diffused charge distribution. This enables us to clarify the interplay of charge and spin degrees of freedom. In the two-dimensional case, a well-separated two-step relaxation is observed; the slower spin relaxation follows the faster charge relaxation as a result of the coupling between the spin and charge degrees of freedom. This shows that the spin-charge separation approximately holds and the coupling between the spin and charge degrees of freedom is weak. In the one-dimensional case, only the charge relaxation is observed. Furthermore, there is no correlation between the relaxations before and after the second pulse. These are characteristic behaviors inherent in the spin-charge separation in strongly correlated electron systems.