Spinon confinement in the one dimensional Ising like antiferromagnet SrCo2V2O8

For quasi one dimensional quantum spin systems theory predicts the occurrence of a confinement of spinon excitation due to interchain couplings. Here we investigate the system SrCo2V2O8, a realization of the weakly coupled Ising like XXZ antiferromagnetic chains, by terahertz spectroscopy with and without applied magnetic field. At low temperatures a series of excitations is observed, which split in a Zeeman like fashion in an applied magnetic field. These magnetic excitations are identified as the theoretically predicted spinon pair excitations. Using a one dimensional Schr odinger equation with a linear confinement potential imposed by weak interchain couplings, the hierarchy of the confined spinons can be fully describe