Large magnetoresistance in the iron-free pnictide superconductor LaRu$_2$P$_2$

TL;DR

This study reports large, non-saturating magnetoresistance in LaRu₂P₂, a superconductor lacking strong electron correlations, attributed to its unique 3D Fermi surface and open orbits, contrasting with correlated Fe-based pnictides.

Contribution

It demonstrates that large magnetoresistance can occur in iron-free pnictides without electron-electron correlations, linked to their Fermi surface topology.

Findings

Magnetoresistance follows H^{1.3} up to 22 T.

LaRu₂P₂ has a 3D Fermi surface with negligible bandwidth renormalization.

Large magnetoresistance is due to open orbits, not electron correlations.

Abstract

The magnetoresistance of iron pnictide superconductors is often dominated by electron-electron correlations and deviates from the H$^2$ or saturating behaviors expected for uncorrelated metals. Contrary to similar Fe-based pnictide systems, the superconductor LaRu$_2$P$_2$ (T$_c$ = 4 K) shows no enhancement of electron-electron correlations. Here we report a non-saturating magnetoresistance deviating from the H$^2$ or saturating behaviors in LaRu$_2$P$_2$. We have grown and characterized high quality single crystals of LaRu$_2$P$_2$ and measured a magnetoresistance following H$^{1.3}$ up to 22 T. We discuss our result by comparing the bandstructure of LaRu$_2$P$_2$ with Fe based pnictide superconductors. The different orbital structures of Fe and Ru leads to a 3D Fermi surface with negligible bandwidth renormalization in LaRu$_2$P$_2$, that contains a large open sheet over the whole Brillouin zone. We show that the large magnetoresistance in LaRu$_2$P$_2$ is unrelated to the one obtained in materials with strong electron-electron correlations and that it is compatible instead with conduction due to open orbits on the rather complex Fermi surface structure of LaRu$_2$P$_2$.