Direct Observation of Magnon Fractionalization in the Quantum Spin Ladder
B. Thielemann, Christian Rüegg, Henrik Moodysson Rønnow +12 more
We measure by inelastic neutron scattering the spin excitation spectra as a function of applied magnetic field in the quantum spin-ladder material (C5H12N)2CuBr4. Discrete magnon modes at low fields in the quantum disordered phase and at high fields in the saturated phase contrast sharply with a spinon continuum at intermediate fields characteristic of the Luttinger-liquid phase. By tuning the magnetic field, we drive the fractionalization of magnons into spinons and, in this deconfined regime, observe both commensurate and incommensurate continua.
arXiv:0812.3880•Physical Review Letters•Mar 13, 2009•116 citations