Thermal transport properties of disordered spin-1/2 systems

This work studies heat transport of bond-disordered spin-1/2 chains. As an example, the XX case is analyzed, which corresponds to a model of noninteracting spinless fermions. Within the fermion representation, the single-particle eigenenergies are determined numerically, which allow one to compute transport coefficients. Since the ballistic transport properties of a clean chain are destroyed by disorder, the focus is on the frequency dependence of the thermal conductivity and on a qualitative comparison with the spin conductivity, both at finite temperatures.Comment: 2 pages, 1 figure. To be published in the Proceedings of SCES '05, Vienna, in Physica

Transport in dimerized and frustrated spin systems

We analyze the Drude weight for both spin and thermal transport of one-dimensional spin-1/2 systems by means of exact diagonalization at finite temperatures. While the Drude weights are non-zero for finite systems, we find indications of a vanishing of the Drude weights in the thermodynamic limit for non-integrable models implying normal transport behavior.Comment: 2 pages, 1 figure. Proceedings of the ICM 2003, Rom

Domain-wall melting as a probe of many-body localization

Motivated by a recent optical-lattice experiment by Choi et al.[Science 352, 1547 (2016)], we discuss how domain-wall melting can be used to investigate many-body localization. First, by considering noninteracting fermion models, we demonstrate that experimentally accessible measures are sensitive to localization and can thus be used to detect the delocalization-localization transition, including divergences of characteristic length scales. Second, using extensive time-dependent density matrix renormalization group simulations, we study fermions with repulsive interactions on a chain and a two-leg ladder. The extracted critical disorder strengths agree well with the ones found in existing literature.Comment: 4+2 pages, 4+2 figure