# Low energy inelastic response in the superconducting phases of $PrOs_4Sb_{12}$

## TL;DR

This paper investigates the low energy inelastic response in the superconducting phases of PrOs4Sb12, providing a microscopic model, Ginzburg-Landau theory, and Raman spectroscopy techniques to identify gap structures and symmetry-breaking phenomena.

## Contribution

It introduces a microscopic derivation of the Ginzburg-Landau expansion and proposes Raman spectroscopy methods to distinguish gap symmetries in PrOs4Sb12's superconducting phases.

## Key findings

- Identification of low energy spectral weight differences in A and B phases.
- Proposal of Raman spectroscopy geometries to determine gap symmetries.
- Potential to locate nodes on the Fermi surface based on spectral features.

## Abstract

Recent AC susceptibility and polar Kerr effect measurements in the skutterudite superconductor PrOs4Sb12 (POS) uncovered the nature of the superconducting double transition from a high temperature, high field, time reversal symmetric phase (or the A phase) to a low temperature, low field, time reversal symmetry broken phase (or the B phase). Starting from a microscopic model, we derive a Ginzburg-Landau expansion relevant to POS that describes this entrance into the time reversal symmetry broken phase along the temperature axis. We also provide a study of the low energy inelastic (Raman) response in both the A and B phases of POS, and seek additional signatures which could help reveal the exact form of the gap functions previously proposed in these phases. By appropriately manipulating the incoming and scattered light geometries, along with additional subtraction procedures and suitable assumptions, we show that one can access the various irreducible representations contained in the point group describing POS. We demonstrate how to use this technique on example order parameters proposed in POS. Depending on whether there exist nodes along the c-axis, we find additional low energy spectral weight within the superconducting gap in the Eg geometry, a feature that could pin point the location of nodes on the Fermi surface.