Spinon confinement and the quantum criticality in the weakly coupled spin-ladder compound CaCu2O3 – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > 2009 > Spinon confinement and...

Spinon confinement and the quantum criticality in the weakly coupled spin-ladder compound CaCu2O3

Spinon confinement and the quantum criticality in the weakly coupled spin-ladder compound CaCu2O3

Confinement describes how constituent particles are bound together by a confining interaction to form a resultant particle (e.g. confinement of 3 quarks to form a hadron). In condensed matter, confinement occurs in spin-ladders (two spin-1/2 Heisenberg, antiferromagnetic chains coupled together). Excitations of individual chains are spinons but an infinitesimal inter-chain coupling confines them. All current ladders have large inter-chain interactions and are in the strong confinement limit with magnon excitations and are thus unable to reveal the confinement process. Here we present neutron scattering experiments on a weakly-coupled spin-ladder, which displays all the theoretically predictions of confinement including the bound-spinon singlet mode which is absent at strong coupling. This system is at the long sought after Wess-Zumino-Novikov-Witten quantum critical point which is predicted to also govern the =5/2 Fractional Quantum Hall effect, and the S=1 chain with biquadratic exchange.

Talk by Bella Lake