A de Haas-van Alphen study of the filled skutterudite compounds PrOs$_4$As$_{12}$ and LaOs$_4$As$_{12}$

TL;DR

This study investigates the Fermi surface and magnetic properties of PrOs$_4$As$_{12}$ and LaOs$_4$As$_{12}$ using high-field magnetic measurements, revealing differences in electron correlations and magnetic behavior.

Contribution

It provides detailed de Haas-van Alphen data on filled skutterudites, highlighting the role of 4f electrons and magnetic fluctuations in their electronic structure.

Findings

PrOs$_4$As$_{12}$ exhibits metamagnetic transitions and magnetic fluctuations.

Fermi surfaces of PrOs$_4$As$_{12}$ and LaOs$_4$As$_{12}$ are similar and match bandstructure predictions.

Effective masses decrease with increasing magnetic field in PrOs$_4$As$_{12}$.

Abstract

Comprehensive magnetic-field-orientation dependent studies of the susceptibility and de Haas-van Alphen effect have been carried out on single crystals of the filled skutterudites PrOs$_4$As$_{12}$ and LaOs$_4$As$_{12}$ using magnetic fields of up to 40~T. Several peaks are observed in the low-field susceptibility of PrOs$_4$As$_{12}$, corresponding to cascades of metamagnetic transitions separating the low-field antiferromagnetic and high-field paramagnetic metal (PMM) phases. The de Haas-van Alphen experiments show that the Fermi-surface topologies of PrOs$_4$As$_{12}$ in its PMM phase and LaOs$_4$As$_{12}$ are very similar. In addition, they are in reasonable agreement with the predictions of bandstructure calculations for LaOs$_4$As$_{12}$ on the PrOs$_4$As$_{12}$ lattice. Both observations suggest that the Pr 4$f$ electrons contribute little to the number of itinerant quasiparticles in the PMM phase. However, whilst the properties of LaOs$_4$As$_{12}$ suggest a conventional nonmagnetic Fermi liquid, the effects of direct exchange and electron correlations are detected in the PMM phase of PrOs$_4$As$_{12}$. For example, the quasiparticle effective masses in PrOs$_4$As$_{12}$ are found to decrease with increasing field, probably reflecting the gradual suppression of magnetic fluctuations associated with proximity to the low-temperature, low-field antiferromagnetic state.