Ultrasonic observation of small Fermi surfaces in La$T$In$_5$ ($T$ = Co, Rh, Ir)

TL;DR

This study used ultrasonic measurements to detect small Fermi surfaces in La$T$In$_5$ compounds, revealing their bulk origin and the role of transition metal $3d$ electrons, with implications for understanding their electronic structure.

Contribution

First observation of small Fermi surfaces in La$T$In$_5$ compounds via ultrasonic quantum oscillation measurements, highlighting the contribution of transition metal $3d$ electrons.

Findings

Quantum oscillations from small Fermi surfaces in LaRhIn$_5$.

Detection of hidden Fermi surfaces in LaCoIn$_5$ and LaIrIn$_5$.

Transition metal $3d$ electrons contribute to small Fermi surfaces.

Abstract

We performed high-field ultrasonic measurements on La$T$In$_5$ ($T$ = Co, Rh, Ir) to reveal the origin of the small Fermi surface that was recently observed in LaRhIn$_5$ with an oscillation frequency of 6.8 T. We observed quantum oscillations originating from this Fermi surface in LaRhIn$_5$. In addition, we revealed that LaCoIn$_5$ and LaIrIn$_5$ exhibit quantum osciilations with frequencies below 100 T, indicating hidden Fermi surfaces in these compounds. Furthermore, Co-substituted LaRhIn$_5$ exhibited quantum oscillations with a frequency of 10 T. Our results suggest that the small Fermi surface originates from bulk properties and that $3d$ electrons of the transition metal contribute to its formation.