Orbital order and Hund's rule frustration in Kondo lattices

TL;DR

This paper investigates how the Kondo effect influences orbital order in heavy-fermion materials, revealing a frustration-driven spiral order that appears within the heavy-electron phase and can be experimentally observed.

Contribution

It introduces a microscopic model showing that Hund's rule frustration due to the Kondo effect induces incommensurate spiral orbital and magnetic order in heavy-fermion systems.

Findings

Spiral orbital and magnetic order exists only within the Kondo screened phase.

The order can be detected via neutron and resonant X-ray scattering.

The phenomena can be realized in cold atomic gases like fermionic ${}^{173}{ m Yb}$.

Abstract

We analyze a microscopic origin of the Kondo effect-assisted orbital order in heavy-fermion materials. By studying the periodic two-orbital Anderson model with two local electrons, we show that frustration of Hund's rule coupling due to the Kondo effect leads to an incommensurate spiral orbital and magnetic order, which exists only inside the Kondo screened (heavy-electron) phase. This spiral state can be observed in neutron and resonant X-ray scattering measurements in ${\rm U}$- and ${\rm Pr}$-based heavy-fermion compounds, and realized in cold atomic gases, e.g. fermionic ${}^{173}{\rm Yb}$.