Low temperature specific heat of the heavy fermion superconductor PrOs$_4$Sb$_{12}$

TL;DR

This study investigates the low temperature specific heat of PrOs$_4$Sb$_{12}$, revealing a doublet ground state and suggesting unconventional superconductivity mediated by quadrupolar fluctuations, not electron-phonon or magnetic interactions.

Contribution

It provides the first detailed magnetic field dependence of specific heat in PrOs$_4$Sb$_{12}$, supporting a non-traditional pairing mechanism in this heavy fermion superconductor.

Findings

Evidence of a doublet ground state

Superconductivity mediated by quadrupolar fluctuations

Distinct magnetic phase diagram

Abstract

We report the magnetic field dependence of the low temperature specific heat of single crystals of the first Pr-based heavy fermion superconductor PrOs$_4$Sb$_{12}$. The low temperature specific heat and the magnetic phase diagram inferred from specific heat, resistivity and magnetisation provide compelling evidence of a doublet ground state and hence superconductivity mediated by quadrupolar fluctuations. This establishes PrOs$_4$Sb$_{12}$ as a very strong contender of superconductive pairing that is neither electron-phonon nor magnetically mediated.