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Spinon Confinement and a Sharp Longitudinal Mode in Yb2Pt2Pb in Magnetic Fields



W. J. Gannon, I. A. Zaliznyak, L. S. Wu, A. E. Feiguin, A. M. Tsvelik, F. Demmel, Yiming Qiu, John R. Copley, M. S. Kim, M. C. Aronson


The fundamental excitation of spin chain systems is the spinon, which is a deconfined quasiparticle with fractionalized spin. Coupling spin chains leads to the confinement of these spinons, a condensed matter analog of quark confinement in quantum chromodynamics. We have discovered that modest magnetic fields can tune the relative strengths of the intra- and interchain couplings in Yb2Pt2Pb providing unprecedented access to the transition to spinon confinement. The high resolution neutron scattering experiments reported here detail how the angular momentum and energy of freely propagating spinons are continuously transformed into a new family of quasiparticles that define a distinctive Fermi surface, a process that is well described by DMRG calculations. A coherent interchain relieves the frustration of quasiparticles on neighboring chains, but in contrast to the transverse spin waves found in conventional magnets, the Ising nature of the Yb moments in Yb2Pt2Pb ensures that this new mode is purely longitudinal.
Nature Communications


spinon confinement, neutron scattering, longitudinal mode, spin chain


Gannon, W. , Zaliznyak, I. , Wu, L. , Feiguin, A. , Tsvelik, A. , Demmel, F. , Qiu, Y. , Copley, J. , Kim, M. and Aronson, M. (2019), Spinon Confinement and a Sharp Longitudinal Mode in Yb<sub>2</sub>Pt<sub>2</sub>Pb in Magnetic Fields, Nature Communications, [online], (Accessed December 5, 2023)
Created March 7, 2019, Updated October 12, 2021