title: Optical conductivity measurements of GaTa4Se8 under high pressure: evidence of a bandwidth-controlled insulator-to-metal Mott transition.
abstract: The optical properties of a GaTa(4)Se(8) single crystal are investigated under high pressure. At ambient pressure, the optical conductivity exhibits a charge gap of ≈0.12 eV and a broad midinfrared band at ≈0.55 eV. As pressure is increased, the low energy spectral weight is strongly enhanced and the optical gap is rapidly filled, pointing to an insulator to metal transition around 6 GPa. The overall evolution of the optical conductivity demonstrates that GaTa(4)Se(8) is a Mott insulator which undergoes a bandwidth-controlled Mott metal-insulator transition under pressure, in remarkably good agreement with theory. With the use of our optical data and ab initio band structure calculations, our results were successfully compared to the (U/D, T/D) phase diagram predicted by dynamical mean field theory for strongly correlated systems.
authors: GREMAN, CNRS UMR 7347-CEA, Université F. Rabelais, UFR Sciences, Tours, France.
authors: V
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authors: Ta Phuoc
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authors: Vaju
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authors: Corraze
authors: R
authors: R
authors: Sopracase
authors: A
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authors: Perucchi
authors: C
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authors: Marini
authors: P
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authors: Postorino
authors: M
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authors: Chligui
authors: S
authors: S
authors: Lupi
authors: E
authors: E
authors: Janod
authors: L
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authors: Cario