We study the magnetic excitations on top of the plateaux states recently discovered in spin-Peierls systems in a magnetic field. We show by means of extensive density matrix renormalization group (DMRG) computations and an analytic approach that one single spin-flip on top of M=1−N2 (N=3,4,...) plateau decays into N elementary excitations each carrying a fraction N1 of the spin. This fractionalization goes beyond the well-known decay of one magnon into two spinons taking place on top of the M=0 plateau. Concentrating on the 31 plateau (N=3) we unravel the microscopic structure of the domain walls which carry fractional spin-31, both from theory and numerics. These excitations are shown to be noninteracting and should be observable in x-ray and nuclear magnetic resonance experiments.
@article{arxiv.cond-mat/0608326,
title = {Excitations with fractional spin less than 1/2 in frustrated magnetoelastic chains},
author = {C. J. Gazza and A. O. Dobry and D. C. Cabra and T. Vekua},
journal= {arXiv preprint arXiv:cond-mat/0608326},
year = {2015}
}
Comments
6 pages, 5 figures. Accepted to be published in Phys. Rev. B