Robust tunability of magnetorestance in Half-Heusler RPtBi (R = Gd, Dy, Tm, and Lu) compounds

TL;DR

This study investigates the magnetic field-dependent transport properties of RPtBi half-Heusler compounds, revealing large, tunable magnetoresistance and complex Hall effects, with potential for advanced magnetic and thermoelectric applications.

Contribution

It demonstrates the tunability of magnetoresistance in RPtBi compounds through lanthanide contraction and explores the underlying mechanisms of non-trivial MR behavior.

Findings

Large non-saturating MR up to 300 K under moderate fields

Sign change in Hall coefficient for Gd-based compound around 120 K

Enhanced thermoelectric power under magnetic field, up to 100 μV/K

Abstract

We present the magnetic field dependencies of transport properties for $R$PtBi ($R$ = Gd, Dy, Tm, and Lu) half-Heusler compounds. Temperature and field dependent resistivity measurements of high quality $R$PtBi single crystals reveal an unusually large, non-saturating magnetoresistance (MR) up to 300 K under a moderate magnetic field of $H$ = 140 kOe. At 300 K, the large MR effect decreases as the rare-earth is traversed from Gd to Lu and the magnetic field dependence of MR shows a deviation from the conventional $H^{2}$ behavior. The Hall coefficient ($R_{H}$) for $R$ = Gd indicates a sign change around 120 K, whereas $R_{H}$ curves for $R$ = Dy, Tm, and Lu remain positive for all measured temperatures. At 300 K, the Hall resistivity reveals a deviation from the linear field dependence for all compounds. Thermoelectric power measurements on this family show strong temperature and magnetic field dependencies which are consistent with resistivity measurements. A highly enhanced thermoelectric power under applied magnetic field is observed as high as $\sim$100 $\mu$V/K at 140 kOe. Analysis of the transport data in this series reveals that the rare-earth-based Half-Husler compounds provide opportunities to tune MR effect through lanthanide contraction and to elucidate the mechanism of non-trivial MR.