Charge-Density-Wave Ordering in the Metal-Insulator Transition Compound PrRu4P12

TL;DR

This study reveals charge density wave ordering in PrRu4P12 associated with its metal-insulator transition, supported by structural and diffraction evidence indicating a low-temperature insulating phase.

Contribution

It provides direct experimental evidence of charge density wave ordering in PrRu4P12 and links it to the metal-insulator transition mechanism.

Findings

Charge density wave ordering appears below the transition temperature.

Structural symmetry changes from Im-3 to Pm-3.

Superlattice peak intensity follows the squared BCS function.

Abstract

X-ray and electron diffraction measurements on the metal-insulator (M-I) transition compound PrRu$_4$P$_{12}$ have revealed the emergence of a periodic ordering of charge density around the Pr atoms. It is found that the ordering is associated with the onset of a low temperature insulator phase. These conclusions are supported by the facts that the space group of the crystal structure transforms from Im$\bar{3}$ to Pm$\bar{3}$ below the M-I transition temperature and also that the temperature dependence of the superlattice peaks in the insulator phase follows the squared BCS function. The M-I transition could be originated from the perfect nesting of the Fermi surface and/or the instability of the $f$ electrons.