One-dimensional repulsive Hubbard model with mass imbalance: Orders and filling anomaly

TL;DR

This paper explores the phase diagram of a one-dimensional repulsive Hubbard model with mass imbalance, revealing a topological triplet paired phase, filling anomalies, and additional phases at specific fillings, using DMRG and theoretical analysis.

Contribution

It identifies a novel topological triplet paired phase and characterizes filling anomalies and additional phases at 1/3 filling in the mass-imbalanced Hubbard model.

Findings

Discovery of a triplet paired phase ($ ext{SG}$) at generic fillings.

Identification of filling anomalies related to symmetry and gap relations.

Observation of crystal and trion phases at 1/3 filling.

Abstract

We investigate the phase diagram of the one-dimensional repulsive Hubbard model with mass imbalance. Using DMRG, we show that this model has a "triplet" paired phase (dubbed $\pi \mathrm{SG}$) at generic fillings, consistent with previous theoretical analysis. We study the topological aspect of $\pi \mathrm{SG}$ phase, determining long-range string orders and the filling anomaly which refers to the relation among the single particle gap, inversion symmetry, and filling imbalance for open chains. We also find, using DMRG, that at $1/3$ filling, commensurate effects lead to two additional phases: a crystal phase and a trion phase; we construct a description of these phases using Tomonaga-Luttinger liquid theory.