Extremely Large Magnetoresistance and Anisotropic Transport in Multipolar Kondo System PrTi$_{2}$Al$_{20}$

TL;DR

This study reveals that PrTi$_{2}$Al$_{20}$ exhibits extremely large, anisotropic magnetoresistance linked to its multipolar Kondo state and ferroquadrupolar order, challenging conventional explanations based on carrier compensation.

Contribution

It demonstrates the role of open-orbit Fermi surface topology and quadrupolar order in producing giant, anisotropic magnetoresistance in a multipolar Kondo system.

Findings

PrTi$_{2}$Al$_{20}$ shows ~1000% XMR below 2 K.

XMR violates Kohler's scaling and is linked to Fermi surface topology.

Transport anisotropy correlates with quadrupolar order parameter response.

Abstract

Multipolar Kondo systems offer unprecedented opportunities for designing astonishing quantum phases and functionalities beyond spin-only descriptions. A model material platform of this kind is the cubic heavy-fermion system Pr$Tr_{2}$Al$_{20}$ ($Tr=$ Ti, V), which hosts a nonmagnetic crystal-electric-field (CEF) ground state and substantial Kondo entanglement of the local quadrupolar and octopolar moments with the conduction electron sea. Here, we explore magnetoresistance (MR) and Hall effect of PrTi$_{2}$Al$_{20}$ that develops ferroquadrupolar (FQ) order below $T_{Q} \sim 2$ K and compare its behavior with that of the non-4$f$ analog, LaTi$_{2}$Al$_{20}$. In the FQ ordered phase, PrTi$_{2}$Al$_{20}$ displays extremely large magnetoresistance (XMR) of $\sim 10^{3}\%$. The unsaturated, quasi-linear field ($B$) dependence of the XMR violates the conventional Kohler's scaling and defies description based on carrier compensation alone. By comparing the MR and the Hall effect observed in PrTi$_{2}$Al$_{20}$ and LaTi$_{2}$Al$_{20}$, we conclude that the open-orbit topology on the electron-type Fermi surface (FS) sheet is key for the observed XMR. The low-temperature MR and the Hall resistivity in PrTi$_{2}$Al$_{20}$ display pronounced anisotropy in the [111] and [001] magnetic fields, which is absent in LaTi$_{2}$Al$_{20}$, suggesting that the transport anisotropy ties in with the anisotropic magnetic-field response of the quadrupolar order parameter.