Orbital ordering of ultracold alkaline-earth atoms in optical lattices

Andrii Sotnikov,Yeimer Zambrano,Agnieszka Cichy,Nelson Darkwah Oppong

doi:10.1103/physrevresearch.2.023188

Abstract

We report on a dynamical mean-field theoretical analysis of emerging low-temperature phases in multicomponent gases of fermionic alkaline-earth(-like) atoms in state-dependent optical lattices. Using the example of $^{173}$Yb atoms, we show that a two-orbital mixture with two nuclear spin components is a promising candidate for studies of not only magnetic but also staggered orbital ordering peculiar to certain solid-state materials. We calculate and study the phase diagram of the full Hamiltonian with parameters similar to existing experiments and reveal an antiferroorbital phase. This long-range-ordered phase is inherently stable, and we analyze the change of local and global observables across the corresponding transition lines, paving the way for experimental observations. Furthermore, we suggest a realistic extension of the system to include and probe a Jahn-Teller source field playing one of the key roles in real crystals.

Highlights

In solid-state materials, electrons can occupy different orbital states, which usually determine their directional mobility
We report on the possibility to approach and simulate orbital ordering with alkaline-earth(-like) atoms (AEAs) in statedependent optical lattice (SDL)
We show that AEAs in SDLs are promising candidates for the experimental observations of orbital ordering phenomena and potentially could improve the understanding of related mechanisms in solid-state materials

Summary

Introduction

In solid-state materials, electrons can occupy different orbital states, which usually determine their directional mobility. Transitions to this long-range-ordered phase result in noticeable changes of experimentally-accessible observables, which we determine for the fraction of doubly-occupied lattice sites, the orbital density distribution in a harmonic trap, and nearest-neighbor

Results

Conclusion