Anomalous properties in the low-carrier ordered phase of PrRu4P12: Consequence of hybridization between conduction and Pr 4f electrons

TL;DR

This study investigates the low-temperature phase of PrRu4P12, revealing anomalous electronic properties likely caused by hybridization between conduction electrons and Pr 4f electrons, indicating a semimetal-like ground state.

Contribution

It provides experimental evidence of Fermi surface decimation and anomalous behaviors linked to c-f hybridization in PrRu4P12 below the metal-non-metal transition.

Findings

Large thermoelectric power ~-200 μV/K below 30 K

Giant negative magnetoresistance of 93% at ~0.4 K

Evidence of a semimetal-like ground state

Abstract

The low-carrier ordered phase below the metal-non-metal transition temperature T_MI ~ 63 K of PrRu4P12 is explored by probing magnetoresistance, magnetic susceptibility, thermoelectric power, and Hall effect on high quality single crystals. All the measured properties exhibit the signature of decimation of the Fermi surface below T_MI and anomalous behaviors below 30 K including a large thermoelectric power ~-200 uV/K and a giant negative magnetoresistance (93% at ~0.4 K). The results indicate an additional structure below 30 K and a semimetal-like ground state. The observed anomalous behaviors are most likely associated with the novel role of c-f hybridization between conduction electrons and Pr 4f electrons, whose crystalline electric field level schemes show drastic change below T_MI.