Orbital phases of $p$-band ultracold fermions in the frustrated triangular lattice

TL;DR

This paper investigates the complex orbital phases of spinless fermions in a frustrated triangular lattice using advanced numerical methods, revealing diverse quantum phases driven by orbital interactions and frustration.

Contribution

It introduces a detailed study of orbital orderings in $p$-band ultracold fermions on a triangular lattice, including an effective orbital-exchange model for understanding phase competition.

Findings

Identification of stripe-, ferro-, and para-orbital phases

Construction of low-temperature phase diagrams

Derivation of an effective orbital-exchange model

Abstract

Orbital degrees of freedom play an important role for understanding the emergence of unconventional quantum phases. Ultracold atomic gases in optical lattices provide a wonderful platform to simulate orbital physics. In this work, we consider spinless fermionic atoms loaded into $p$-orbital bands of a two-dimensional frustrated triangular lattice. The system can be described by an extended Fermi-Hubbard model, which is numerically solved by using the orbital version of real-space dynamical mean-field theory. Low-temperature phase diagrams are obtained, which contain stripe-, ferro- and para-orbital ordered quantum phases, due to the interplay of anisotropic hoppings and geometrical frustration. In order to understand the underlying mechanics of competing orbital orders, we derive an effective orbital-exchange model, which yields consistent explanation with our main numerical results.