SKM 2021 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 9: INNOMAG e.V. Diploma/Master Prize (2021)
MA 9.2: Vortrag
Mittwoch, 29. September 2021, 12:50–13:10, H2
Angle-Dependent Magnetotransport in Semimetals — •Felix Spathelf1,2,3, Benoît Fauqué2, and Kamran Behnia1 — 1LPEM (CNRS), ESPCI Paris, Université PSL, Paris, France — 2JEIP, USR 3573 CNRS, Collège de France, Université PSL, Paris, France — 3Universität Heidelberg
We report on studies of the electrical and thermoelectric transport properties of semimetals with high mobilities at temperatures down to 2 K and in magnetic fields up to 13.8 T to understand their remarkable amplitude. The Seebeck effect, magnetoresistance and the Hall effect of bismuth were measured and compared to the results of a theoretical model, which was developed on the basis of semiclassical theory. The model perfectly describes the zero field Seebeck coefficient from 10 K to 300 K and agrees well with experimental data in a large part of the (T,B,Θ)-space. It is shown that the contribution of the Nernst coefficient to the Seebeck effect has to be taken into account when explaining the latter. In addition, the Seebeck effect of bismuth is at least up to a temperature of 120 K significantly affected by Landau quantisation. Furthermore, the influence of the sample shape on the angle-dependent magnetoresistance is studied in bismuth and antimony. At 40 K, magnetoresistance shows the symmetry inherited from the Fermi surface topology. Upon cooling below 20 K, this symmetry is lost in bismuth, but not in antimony. The loss of symmetry is sample-dependent and can be traced back to a robust surface contribution to conductivity. Besides, the highest magnetoresistance ever observed was measured in bismuth, amounting to 1.56· 108 under a magnetic field of 12.8 T.