Phonon spectrum of Pr$_2$Zr$_2$O$_7$ and Pr$_2$Ir$_2$O$_7$ as an evidence of coupling of the lattice with electronic and magnetic degrees of freedom

TL;DR

This study investigates the phonon spectra of two Praseodymium-based pyrochlores, revealing magneto-elastic and phonon-electron couplings that influence their magnetic and electronic properties, with minimal disorder effects.

Contribution

It provides the first comparative analysis of Raman phonon spectra in Pr$_2$Zr$_2$O$_7$ and Pr$_2$Ir$_2$O$_7$, highlighting lattice-electronic-magnetic coupling mechanisms.

Findings

Magneto-elastic coupling identified in Pr$_2$Zr$_2$O$_7$.

Phonon-electron coupling characterized in Pr$_2$Ir$_2$O$_7$.

Disorder effects on phonon spectra are minimal.

Abstract

Magnetic materials with pyrochlore crystal structure form exotic magnetic states due to the high lattice frustration. In this work we follow the effects of coupling of the lattice and electronic and magnetic degrees of freedom in two Praseodymium-based pyrochlores Pr$_2$Zr$_2$O$_7$ and Pr$_2$Ir$_2$O$_7$. In both materials the presence of magnetic interactions does not lead to magnetically ordered low temperature states, however their electronic properties are different. A comparison of Raman phonon spectra of Pr$_2$Zr$_2$O$_7$ and Pr$_2$Ir$_2$O$_7$ allows us to identify magneto-elastic coupling in Pr$_2$Zr$_2$O$_7$ that elucidates its magnetic properties at intermediate temperatures, and allows us to characterize phonon-electron coupling in the semimetallic Pr$_2$Ir$_2$O$_7$. We also show that the effects of random disorder on the Raman phonon spectra is small.