Wavepacket approach for spin transport in zigzag spin chain

波束アプローチによるジグザグスピン鎖のスピン輸送の研究

大西 弘明  

Onishi, Hiroaki

We investigate the transport property of the spin nematic state in the zigzag spin chain from the perspective of the time evolution of wavepackets by a time-dependent density-matrix renormalization group method. We create a magnon-pair wavepacket in a spin nematic regime, and examine how the wavepacket propagates with keeping its coherence as the time evolves. We find that in the vicinity of the saturation field, a magnon-pair wavepacket of wavenumber remains localized at the initial position. This is because the quadrupole excitation spectrum has a gapless mode due to the antiferro-quadrupole quasi-long-range order, and the gapless dispersion has a rather flat structure, indicating zero propagation velocity. We will present detailed numerical results of the dependence on exchange coupling and magnetic field, and discuss the relationship between magnetic and transport properties.