Orbital currents and cheap vortices in underdoped cuprates

TL;DR

This paper presents a theoretical framework for underdoped cuprates based on an SU(2) formulation of the t-J model, highlighting the role of orbital currents and vortices in explaining their unusual properties.

Contribution

It introduces a novel SU(2) gauge theory approach that links orbital currents and vortices to the behavior of underdoped cuprates, supported by wavefunction analysis.

Findings

Support for orbital currents in the Gutzwiller projected BCS wavefunction

Vortices with stabilized staggered flux in their cores

Proposed experiments to detect orbital currents

Abstract

In the past several years, we have developed a theory for the underdoped cuprates in collaboration with X.-G. Wen, based on an SU(2) formulation of the t-J model. In this formulation, the staggered flux state plays a central role as the progenitor of the Neel state at half-filling and a close competitor to the d-wave superconductor with small doping where it is characterized by staggered orbital currents. We found support for this point of view when we discovered fluctuating orbital currents in the Gutzwiller projected BCS wavefunction. We shall argue that low-energy vortices, where the staggered flux state is stabilized in the core, are needed to explain many of the unusual properties of underdoped cuprates. Proposed experiments to look for these orbital currents will be discussed.