Pressure suppression of unconventional charge-density-wave state in PrRu4P12 studied by optical conductivity

TL;DR

This study investigates how applying high pressure suppresses the unconventional charge-density-wave state in PrRu4P12, revealing a transition from insulating to metallic behavior through optical conductivity measurements.

Contribution

It provides new insights into pressure-induced electronic phase transitions in PrRu4P12 by combining optical conductivity data with pressure and temperature variations.

Findings

Energy gap diminishes with pressure, filling in at 10 GPa.

At 14 GPa, the material exhibits a Drude response indicating metallicity.

Pressure suppresses the charge-density-wave state, inducing a metal-insulator transition.

Abstract

Optical conductivity s(w) of PrRu4P12 has been studied under high pressure to 14 GPa, at low temperatures to 8 K, and at photon energies 12 meV-1.1 eV. The energy gap in s(w) at ambient pressure, caused by a metal-insulator transition due to an unconventional charge-density-wave formation at 63 K, is gradually filled in with increasing pressure to 10 GPa. At 14 GPa and below 30 K, s(w) exhibits a pronounced Drude-type component due to free carriers. This indicates that the initial insulating ground state at zero pressure has been turned into a metallic one at 14 GPa. This is consistent with a previous resistivity study under pressure, where the resistivity rapidly decreased with cooling below 30 K at 14 GPa. The evolution of electronic structure with pressure is discussed in terms of the hybridization between the 4f and conduction electrons.