Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 89: Disordered Quantum Systems

TT 89.4: Talk

Thursday, March 15, 2018, 12:15–12:30, HFT-FT 131

Spectral densities of disordered quantum spin ladders — •Max Hörmann, Paul Wunderlich, and Kai Phillip Schmidt — Institut für Theoretische Physik, FAU Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen

We investigate the zero-temperature dynamic structure factor of a two-leg spin-1/2 Heisenberg ladder with quenched disorder relevant for inelastic neutron scattering. To this end we apply perturbative continuous unitary transformations about the limit of isolated rungs using a white-graph expansion [1] to derive the physical properties of the elementary triplon and two-triplon excitations of the disordered spin ladder in the thermodynamic limit. Here we study bimodal disorder on rungs and legs realizable in experiments by intential doping of existing spin-ladder compounds. The effect of disorder on the two-triplon properties is calculated with high precision in the weakly-coupled rung regime and with that the fate of the bound states is predicted. For the material class of BPCB_xC_1−x one- and two-triplon neutron scattering responses are calculated in both symmetry sectors.
K. Coester and K.P. Schmidt, Phys. Rev. E 92, 022118 (2015).