Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 44: Correlated Electrons: Quantum-Critical Phenomena – Experiments
TT 44.4: Vortrag
Dienstag, 17. März 2015, 14:45–15:00, H 3005
High-pressure Fermi surface of Mott insulator NiS2 — •Sven Friedemann1,2, Hui Chang2, Monica Gamza3, William Coniglio4, David Graf4, Stan Tozer4, and F Malte Grosche2 — 1HH Wills Laboratory, University of Bristol, UK — 2Cavendish Laboratory, University of Cambridge, Cambridge, UK — 3Department of Physics, Royal Holloway University of London, Egham, UK — 4National High Magnetic Field Laboratory, Tallahassee, USA
Metals can turn into insulators when correlations become sufficiently strong. This is captured in the Mott-Hubbard model where onsite Coulomb repulsion leads to the opening of a gap at the Fermi energy for a half-filled band. This insulating state is realized for instance in the parent compounds of cuprate superconductors. Whilst cuprates are turned into metals by controlling the filling, i.e. doping, the metallic state can also be recovered by controlling the ratio of Coulomb repulsion and kinetic energy as can be done by pressure tuning. For this case, Luttinger theorem dictates the electrons to localize via a divergence of the effective mass [1]. Here, we report resistivity and quantum oscillation measurements on the pressure-induced insulator-to-metal transition in the Mott insulator NiS2. We demonstrate the quality of our single crystals, discuss the phase diagram and present Fermi surface measurements in comparison with band structure calculations of the non-correlated case. We discuss these results in the light of the theoretical model.
[1] W. F. Brinkman, T. M. Rice; Phys Rev B; 10 4302 (1970).