Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 35: PhD Symposium: Quantum Phase Transitions: Emergent Phenomena beyond Elementary Excitations (organized by MA, jDPG)

TT 35.13: Poster

Tuesday, March 17, 2015, 16:15–16:30, EB 301

Fermi surface on the border of Mott transition in NiS₂ — •Hui Chang¹, Sven Friedemann^1,2, Monika Gamza³, William Coniglio⁴, David Graf⁴, Stan Tozer⁴, and Malte Grosche¹ — ¹Cavendish Laboratory, University of Cambridge, UK — ²HH Wills Laboratory, University of Bristol, UK — ³Department of Physics, Royal Holloway, University of London, Egham, UK — ⁴National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA

The transition from a metallic to a correlated, or Mott, insulating state is a long-standing theme of fundamental interest in condensed matter research. Using quantum oscillation measurements in high magnetic fields to probe the electronic Fermi surface and effective carrier mass on the metallic side of the transition could provide much needed microscopic information. In the cuprates, such studies in samples doped into the metallic state have identified the Fermi surface structure in underdoped and overdoped regimes. Because the quantum oscillation signal is strongly suppressed in the presence of disorder, pressure rather than doping should ideally be used to reach the metallic state. We present the first observation of quantum oscillations from a pressure-metallised 3D Mott insulator. NiS₂ can be tuned through the Mott transition at a modest pressure of 30kbar. Quantum oscillations near the Mott transition are observed with the tunnel diode oscillator technique in magnetic fields up to 31T. The main observed oscillation frequency is consistent with the Fermi surface obtained within density functional theory, whereas the effective mass is significantly enhanced over the band mass.