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Heat Transport in Low-Dimensional Quantum Magnets

Dr. Christian Hess, Leibniz Institute for Solid State and Materials Research, Dresden

10.07.2013 at 12:00 


The investigation of transport properties is one of the most fundamental methods in experimental solid state physics, since important information about mobility, scattering, and disspation of quasiparticles can be obtained. The heat conductivity depends strongly on the nature of the heat-carrying quasiparticles and is well understood for electronic and phononic excitations. Some years ago, a new, magnetic mode of heat transport has been discovered in low-dimensional S=1/2 quantum magnets and is intensely studied since then. The magnetic heat conductivity of such quantum magnet materials can be exceptionally large (even at room temperature), dwarfs the phonon heat conduction and thereby leads to an overall magnitude of the heat conductivity which is comparable to that of metals.
After reviewing the main experimental findings on S=1/2 spin planes and spin-ladders, this talk focuses on recent experimental results on one-dimensional S=1/2 Heisenberg chain materials. Evidences for ballistic magnetic transport and magnetic mean free paths of more than one micrometer are found in these materials, i.e. at the length scale of typical spin diffusion lengths in spintronic experiments. The effect of various disorder types (viz. bond disorder, magnetic and non-magnetic site disorder) on this transport phenomenon will be discussed.


B139 - Theresienstr. 39