# Emergent non-Fermi-liquid phenomena in multipolar quantum impurity systems

## TL;DR

This paper theoretically investigates multipolar quantum impurity systems with spin-orbital entanglement, revealing novel non-Fermi liquid ground states with unique properties, expanding understanding beyond traditional Kondo models.

## Contribution

It introduces a new class of non-Fermi liquid states in multipolar impurity systems with quadrupolar and octupolar moments, not fitting existing categories.

## Key findings

- Discovery of non-Fermi liquid ground states characterized by singular power-law behaviors.
- Identification of states outside known multi-channel Kondo non-Fermi liquids.

## Abstract

Discovery of novel spin-orbital entangled quantum ground states paves an important avenue for controllable quantum materials via unique couplings to the lattice and other external perturbations. In this work, motivated by recent experiments on cubic heavy fermion materials with multipolar local moments, we theoretically investigate strongly-interacting spin-orbital entangled quantum ground states in multipolar quantum impurity systems. Here itinerant electrons are interacting with the local moments carrying quadrupolar and octupolar moments, in contrast to the conventional Kondo problem with dipolar local moment. Using perturbative renormalization group methods, we uncover a number of non-Fermi liquid ground states, which are characterized by an absence of well-defined quasiparticles and singular power-law behaviours in physical properties. We show that the non-Fermi liquid states found here are outside the known categories of non-Fermi liquid states in the conventional multi-channel Kondo problem. This work lays a novel ground for the identification of unexpected non-Fermi liquid phases in many strongly spin-orbital-coupled quantum materials.