ESR measurements in the double-chain compound NH4CuCl3which has magnetization plateaus at one-quarter and three-quarters of the saturation magnetization, have been performed in magnetic fields up to 30 T in the frequency range ˜95–762GHz. It is found that the frequency versus field diagrams for H|a and H|b coincide when normalized by the g factors. In each plateau region, a pair of excitations expressed as ω=γ(H-Hlc) and ω=γ(Hhc-H) are observed, where Hlc and Hhc are the lower and higher edge fields of the plateau, respectively. These two modes correspond to the quantum gap in the lower- and higher-field halves in the plateau region.
ASJC Scopus subject areas
- Physics and Astronomy(all)