Conduction of heat in a material via heat currents is a phenomenon analogous to charge transport via electrical currents. Thermoelectric phenomena arise from the entanglement of thermal and electrical transport processes due to (1) heat transport by charge carriers and (2) scattering processes between charge carriers and other heat-carrying quasiparticles, e.g. phonons. By studying the thermal conductivity κ, the thermopower and the Nernst coefficient at low temperatures and magnetic fields, we gain valuable information on charge and heat carriers and low energy excitations. [more]
In high carrier density correlated electron systems, quantum oscillations are usually detected as tiny oscillations of the magnetization of a sample that appear below 1K. This requires extremely precise and low noise measurement techniques. We have developed a magnetometer based on piezoresistive cantilevers for submilimeter-sized samples with a resolution that is 10-20 times better than previous techniques at 700 mK and in strong magnetic fields. The working principle is based on the use of a SQUID as a low temperature amplifier, which we were able to run in fields up to 15T. [more]
The magnetic ac-susceptibility (χac) or differential susceptibility is the physical response of the change of magnetization under the influence of a small alternating magnetic field. The field modulation techniques, where oscillations in the higher order harmonics of the susceptibility are detected, is one of the most sensitive techniques to detect de Haas-van Alphen quantum oscillations and it is suitable to be used also under hydrostatic pressure. [more]
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