Insulating phases of electrons on a zigzag strip in the orbital magnetic field

TL;DR

This paper investigates how an orbital magnetic field induces insulating phases in electrons on a zigzag ladder, revealing a mechanism for metal-insulator transition driven by the interplay of magnetic field and interactions.

Contribution

It demonstrates that an orbital magnetic field introduces a relevant four-fermion Umklapp term, enabling metal-insulator transitions at weak coupling in a two-leg triangular ladder.

Findings

Orbital magnetic field induces a four-fermion Umklapp term.

The system can undergo a metal-insulator transition at weak interactions.

Possible phases include C0S2, C0S1, and C0S0.

Abstract

We consider electrons on a two-leg triangular ladder at half-filling and in an orbital magnetic field. In a two-band regime in the absence of the field, the electronic system remains conducting for weak interactions since there is no four-fermion Umklapp term. We find that in the presence of the orbital field there is a four-fermion Umklapp and it is always relevant for repulsive interactions. Thus in this special ladder, the combination of the orbital magnetic field and interactions provides a mechanism to drive metal-insulator transition already at weak coupling. We discuss properties of the possible resulting phases C0S2 and various C0S1 and C0S0.