Li-induced spin and charge excitations in a spin ladder.


A lithium dopant in a cuprate spin ladder acts as a vacant (nonmagnetic) site accompanied by an extra hole bound by a Coulomb potential. We find that, although the undoped ladder spin gap is not essentially altered by Li doping, a dopant-magnon bound state appears just below the gap. Contrary to Zn-doped ladders, the spin liquid character of a Li-doped… (More)