Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 40: Electronic Structure of Magnetism, Micromagnetism, Computational Magnetism (organized by MA)

TT 40.6: Talk

Tuesday, March 17, 2015, 11:00–11:15, H 0112

Finite temperature and magnetic field transport in 1D quantum magnets — •Xenophon Zotos — Physics Department - University of Crete — Crete Center for Quantum Complexity and Nanotechnology — FORTH - IESL

I'll present recent exact results on the finite temperature and magnetic field magneto-thermal transport in the one dimensional spin-1/2 Heisenberg model obtained using the Bethe ansatz (BA) method. In particular, I'll discuss the behavior of spin Drude weight as a function of magnetic field down to low temperatures. These new results are based on a previous analysis by the author of the spin Drude weight in zero magnetic field.

Furthermore, I'll discuss the thermodynamics, thermal transport and dynamics (ESR), of the spin S=1 easy-plane quasi-one dimensional quantum magnet NiCl2-4SC(NH2)2 (DTN). The analysis is based on an effective spin-1/2 anisotropic (s= 1/2) Heisenberg model description that is put on a firm basis by comparing the thermodynamics of the S=1 model, obtained using TMRG, with exact BA specific heat and magnetisation results for the s=1/2 Heisenberg model. For the thermal conductivity in a magnetic field, Ill compare numerical data on the S=1 model obtained using exact diagonalization techniques to exact results using the BA method. For the ESR data, using a recently developed BA technique, I'll show that the extremely sharp line observed in experiments, is due to a singular excitation to a single excited state.