Dresden 2014 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 56: Liquid and Amorphous Metals IV
MM 56.4: Vortrag
Donnerstag, 3. April 2014, 12:15–12:30, IFW A
Thermal Conductivity of Superconducting Bulk Metallic Glasses in the Temperature Range between 6 mK and 300 K — •Daniel Rothfuss1, Andreas Reiser1, Andreas Fleischmann1, Uta Kühn2, and Christian Enss1 — 1Kirchhoff-Institute for Physics, Heidelberg University, INF 227, 69120 Heidelberg — 2IFW Dresden, Institute for Complex Materials, P.O. Box 270116, 01171 Dresden
Bulk metallic glasses (BMG) are a new and very interesting kind of amorphous materials. Measuring the thermal conductivity provides the possibility to probe the fundamental interactions governing the heat flow in solids. We present the first measurements of the thermal conductivity of two superconducting BMGs in the temperature range from 6 mK to 300 K. Our results show that the thermal conductivity of BMGs can be described by two independent contributions based on conduction electrons and phonons. Above the critical temperature Tc the part based on conduction electrons is determined by defect scattering and reduces rapidly below Tc. Sufficiently far below Tc the thermal conductivity is based on the part of the phonons and can be described by their resonant scattering with tunneling systems. Above Tc the contribution of the phonons can be described successfully within a novel model considering not only electrons and phonons but also localized modes as scattering centres. At ultralow temperatures a new contactless measuring technique was used, which is based on optical heating and paramagnetic temperature sensors that are read out by a SQUID magnetometer.