Anomalous Transport Behavior in Quantum Magnets

Anomalous edge transport in the quantum anomalous Hall state.

We predict by first-principles calculations that thin films of a Cr-doped (Bi,Sb)2Te3 magnetic topological insulator have gapless nonchiral edge states coexisting with the chiral edge state. Such gapless nonchiral states are not immune to backscattering, which would explain dissipative transport in the quantum anomalous Hall (QAH) state observed in this system experimentally. Here, we study the...

Anomalous quantum transport in a thin film.

We present a numerical study of electron transport in a thin film of varying disorder strength with the distance from its surface. A simple tight-binding model is used to describe the system, in which the film is attached to two metallic electrodes and the coupling of this film to the electrodes is illustrated by the Newns-Anderson chemisorption theory. Quite interestingly we observe that, in t...

Far-from-equilibrium spin transport in Heisenberg quantum magnets.

We study experimentally the far-from-equilibrium dynamics in ferromagnetic Heisenberg quantum magnets realized with ultracold atoms in an optical lattice. After controlled imprinting of a spin spiral pattern with an adjustable wave vector, we measure the decay of the initial spin correlations through single-site resolved detection. On the experimentally accessible time scale of several exchange...

Quantum Magnets 2015

Frustrated Quantum Magnets

A description of different phases of two dimensional magnetic insulators is given. The first chapters are devoted to the understanding of the symmetry breaking mechanism in the semi-classical Néel phases. Order by disorder selection is illustrated. All these phases break SU(2) symmetry and are gapless phases with ∆Sz = 1 magnon excitations. Different gapful quantum phases exist in two dimension...