Triplet superconductivity in a one-dimensional ferromagnetic t-J model

TL;DR

This paper explores the phase diagram of a one-dimensional ferromagnetic t-J model, revealing triplet superconductivity coexisting with spin density waves, and transitions to insulating and dimerized phases depending on bandwidth and interactions.

Contribution

It provides the first comprehensive weak-coupling phase diagram of the 1D t-U-J model, including effects of on-site interactions and various magnetic anisotropies.

Findings

Identification of a phase with triplet superconductivity and spin density wave coexistence.

Discovery of a transition to an insulating phase resembling the spin-1/2 XY model.

Observation of long-range dimerized order in weakly anisotropic antiferromagnetic cases.

Abstract

In this paper we study the ground state phase diagram of a one-dimensional $t-U-J$ model, at half-filling. In the large-bandwidth limit and for ferromagnetic exchange with easy-plane anisotropy, a phase with gapless charge and massive spin excitations, characterized by the coexistence of triplet superconducting ($TS$) and spin density wave ($SDW^{z}$) instabilities is realized in the ground state. With reduction of the bandwidth, a transition into an insulating phase showing properties of the spin-1/2 XY model takes place. In the case of weakly anisotropic antiferromagnetic exchange the system shows a long range dimerized (Peierls) ordering in the ground state. The complete weak-coupling phase diagram of the model, including effects of the on-site Hubbard interaction, is obtained.