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TT: Fachverband Tiefe Temperaturen
TT 79: Correlated Magnetism – Transport
TT 79.3: Vortrag
Donnerstag, 12. März 2026, 12:00–12:15, HSZ/0103
Giant thermopower changes due to secondary gradients of electronic properties — •Ulrike Stockert1,2,4, Judith Grafenhorst1, Sarah Krebber3, Kristin Kliemt3, Cornelius Krellner3, and Elena Hassinger4,1,2 — 1Technische Universität Dresden, 01062 Dresden, Germany — 2MPI for Chemical Physics of Solids, 01187 Dresden, Germany — 3Physikalisches Institut, Goethe-Universität Frankfurt, 60438 Frankfurt/M, Germany — 4Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
The diffusion thermopower Sdiff of conventional metals and semiconductors is typically small, being of the order of 10-100 µV/K. It arises from changes of the number and velocity of mobile charge carriers with temperature T due to the energy dependence of the density of states and the T dependence of the Fermi distribution. In simple models for the thermopower, these changes are assumed to be weak, and the materials behave homogeneous. However, if electronic properties as the chemical potential or the charge-carrier mobility exhibit strong T dependencies, any temperature gradient induces also significant gradients of these properties. In our presentation we will show that such a secondary gradient of the electrical conductivity σ may induce giant values of the diffusion thermopower. Using a simple drift-diffusion model and allowing explicitly for gradients of σ, we are able to predict the correct magnitude, shape, and field dependence of the thermopower. Our results open a new route to large thermopower values via gradients of electronic properties.
Keywords: thermopower; CMR