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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 Friedemann^1,2, 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).