iPEPS study of spin symmetry in the doped $t$-$J$ model

TL;DR

This study uses iPEPS to explore how spin symmetry influences competing orders like antiferromagnetism, stripe order, and superconductivity in the doped $t$-$J$ model, revealing the interplay between spin symmetry and emergent phases.

Contribution

It demonstrates the impact of imposing SU(2) versus U(1) spin symmetry in iPEPS simulations on the doped $t$-$J$ model, highlighting the role of spin symmetry in phase competition.

Findings

Stripe order is pinned by long-range antiferromagnetic order.

SU(2) iPEPS favors d-wave singlet pairing and uniform charge distribution.

Imposing different spin symmetries affects the emergence of various orders.

Abstract

We study the two-dimensional $t$-$J$ model on a square lattice using infinite projected entangled pair states (iPEPS). At small doping, multiple orders, such as antiferromagnetic order, stripe order and superconducting order, are intertwined or compete with each other. We demonstrate the role of spin symmetry at small doping by either imposing SU(2) spin symmetry or its U(1) subgroup in the iPEPS ansatz, thereby excluding or allowing spontaneous spin-symmetry breaking respectively in the thermodynamic limit. From a detailed comparison of our simulations, we provide evidence that stripe order is pinned by long-range antiferromagnetic order. We also find that SU(2) iPEPS, which enforces a spin-singlet state, yields a uniform charge distribution and favors d-wave singlet pairing.