Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 100: Correlated Electrons: Other Materials

TT 100.13: Vortrag

Donnerstag, 19. März 2015, 18:15–18:30, H 3005

Pressure-induced semimetal to semiconductor transition in bismuth. — •Konstantin Semeniuk, Philip Brown, Aleksandar Vasiljkovic, and Malte Grosche — University of Cambridge, Cambridge, The United Kingdom

The semimetal bismuth stands out among the elements for its extremely low carrier concentration. This arises from small electron and hole Fermi surface pockets, which amount to about 10^-5 of the Brillouin zone, or one mobile electron per 100,000 atoms. Situated very close to the transition to a semiconductor, the electronic structure can be tuned further by doping with antimony or by applied hydrostatic pressure.

We investigate the electrical resistivity, Hall effect and Shubnikov de Haas oscillations of single crystal bismuth under hydrostatic pressure of up to 25 kbar in a piston cylinder pressure cell. While the temperature dependence of the resistivity is metallic at ambient pressure, it develops a pronounced kink and subsequently a maximum near 40 K with increasing pressure. The maximum shifts towards lower temperature with further increasing pressure until, above about 20 kbar, the resistivity of bismuth resembles that of a narrow-gap semiconductor. These results suggest that the Lifshitz transition from semimetal to semiconductor can indeed be studied in bismuth at pressures less than 25 kbar, at which a structural transition into a fully metallic state takes place. This makes it possible to access ultra-low carrier density states at intermediate pressures, in which the quantum limit can be reached at very low applied fields.