In this paper, we study the dynamical characteristics of magnons generated by the static magnetic dipole-dipole interaction and the external-laser induced dipole-dipole interaction in spin chain within an optical lattice. Specially, we choose a blue-detuned optical lattice and define an effective temperature for the system. We make a comparison between the generation process of magnons and that of photons in an optical vibration cavity. The results show that by suitably choosing the system parameters, the dynamical Casimir effect at finite temperature in the magnon system can be reproduced.In this paper, we study the dynamical characteristics of magnons generated by the static magnetic dipole-dipole interaction and the external-laser induced dipole-dipole interaction in spin chain within an optical lattice. Specially, we choose a blue-detuned optical lattice and define an effective temperature for the system. We make a comparison between the generation process of magnons and that of photons in an optical vibration cavity. The results show that by suitably choosing the system parameters, the dynamical Casimir effect at finite temperature in the magnon system can be reproduced.

Acta Physica SinicaJan 1, 20132 citations

Tunable Magnon Interactions in a Ferromagnetic Spin-1 Chain

Prashant Chauhan, Fahad Mahmood, Hitesh J. Changlani +2 more

NiNb_{2}O_{6} is an almost ideal realization of a 1D spin-1 ferromagnetic Heisenberg chain compound with weak unidirectional anisotropy. Using time-domain THz spectroscopy, we measure the low-energy electrodynamic response of NiNb_{2}O_{6} as a function of temperature and external magnetic field. At low temperatures, we find a magnonlike spin excitation, which corresponds to the lowest energy excitation at q∼0. At higher temperatures, we unexpectedly observe a temperature-dependent renormalization of the spin-excitation energy, which has a strong dependence on field direction. Using theoretical arguments, exact diagonalizations, and finite temperature dynamical Lanczos calculations, we construct a picture of magnon-magnon interactions that naturally explains the observed renormalization. We show how magnetic field strength and direction may be used to directly tune the sign of the magnon-magnon interaction. This unique scenario is a consequence of the spin-1 nature and has no analog in the more widely studied spin-1/2 systems.NiNb_{2}O_{6} is an almost ideal realization of a 1D spin-1 ferromagnetic Heisenberg chain compound with weak unidirectional anisotropy. Using time-domain THz spectroscopy, we measure the low-energy electrodynamic response of NiNb_{2}O_{6} as a function of temperature and external magnetic field. At low temperatures, we find a magnonlike spin excitation, which corresponds to the lowest energy excitation at q∼0. At higher temperatures, we unexpectedly observe a temperature-dependent renormalization of the spin-excitation energy, which has a strong dependence on field direction. Using theoretical arguments, exact diagonalizations, and finite temperature dynamical Lanczos calculations, we construct a picture of magnon-magnon interactions that naturally explains the observed renormalization. We show how magnetic field strength and direction may be used to directly tune the sign of the magnon-magnon interaction. This unique scenario is a consequence of the spin-1 nature and has no analog in the more widely studied spin-1/2 systems.

arXiv:1907.06542Physical Review LettersJan 23, 202028 citations

Propagating spinons and magnons in coupled quantum spin chains

Xianglin Ke

Bulletin of the American Physical SocietyMar 16, 20210 citations

Finite temperature dynamics of the spin-half Heisenberg chain

Oleg A. Starykh, Anders W. Sandvik, Rajiv R. P. Singh

Physica B Condensed MatterDec 1, 19974 citations

Finite-temperature dynamics of the spin- 12 bond alternating Heisenberg antiferromagnetic chain

H.-J. Mikeska, C. Luckmann

We present results for the dynamic structure factor of the $S=1∕2$ bond alternating Heisenberg chain over a large range of frequencies and temperatures. Data are obtained from a numerical evaluation of thermal averages based on the calculation of all eigenvalues and eigenfunctions for chains of up to 20 spins. Interpretation is guided by the exact temperature dependence in the noninteracting dimer limit which remains qualitatively valid up to an interdimer exchange $\ensuremath{\lambda}\ensuremath{\approx}0.5$. The temperature induced central peak around zero frequency is clearly identified and aspects of the crossover to spin diffusion in its variation from low to high temperatures are discussed. The one-magnon peak acquires an asymmetric shape with increasing temperature. The two-magnon peak is dominated by the $S=1$ bound state which remains well defined up to temperatures of the order of $J$ . The variation with temperature and wave vector of the integrated intensity for one-magnon and two-magnon scattering and of the central peak are discussed.We present results for the dynamic structure factor of the $S=1∕2$ bond alternating Heisenberg chain over a large range of frequencies and temperatures. Data are obtained from a numerical evaluation of thermal averages based on the calculation of all eigenvalues and eigenfunctions for chains of up to 20 spins. Interpretation is guided by the exact temperature dependence in the noninteracting dimer limit which remains qualitatively valid up to an interdimer exchange $\ensuremath{\lambda}\ensuremath{\approx}0.5$. The temperature induced central peak around zero frequency is clearly identified and aspects of the crossover to spin diffusion in its variation from low to high temperatures are discussed. The one-magnon peak acquires an asymmetric shape with increasing temperature. The two-magnon peak is dominated by the $S=1$ bound state which remains well defined up to temperatures of the order of $J$. The variation with temperature and wave vector of the integrated intensity for one-magnon and two-magnon scattering and of the central peak are discussed.

arXiv:cond-mat/0602387Physical Review BMay 19, 200619 citations

We present results for the dynamic structure factor of the

S=1∕2

bond alternating Heisenberg chain over a large range of frequencies and temperatures. Data are obtained from a numerical evaluation of thermal averages based on the calculation of all eigenvalues and eigenfunctions for chains of up to 20 spins. Interpretation is guided by the exact temperature dependence in the noninteracting dimer limit which remains qualitatively valid up to an interdimer exchange $\ensuremath{\lambda}\ensuremath{\approx}0.5$. The temperature induced central peak around zero frequency is clearly identified and aspects of the crossover to spin diffusion in its variation from low to high temperatures are discussed. The one-magnon peak acquires an asymmetric shape with increasing temperature. The two-magnon peak is dominated by the

S=1

bound state which remains well defined up to temperatures of the order of

J

. The variation with temperature and wave vector of the integrated intensity for one-magnon and two-magnon scattering and of the central peak are discussed.