Quantum String Liquid State in LaOFeAs and Superconductivity

TL;DR

This paper proposes that LaOFeAs exhibits a quantum string liquid state due to coupled valence bond systems, which leads to high-temperature superconductivity through charge condensation of open strings.

Contribution

It introduces a novel quantum string liquid model for LaOFeAs, linking valence bond coupling and superconductivity, offering a new perspective beyond traditional theories.

Findings

Presence of a quantum string liquid state in LaOFeAs.

Doped holes create open strings that condense into superconductivity.

Higher Tc possible when competing orders are suppressed.

Abstract

Superconducting LaOFeAs family of even electron metallic systems have striking resemblance to odd electron cuprates. We suggest that this resemblance is caused by presence of two coupled 2D resonating valence bond systems in LaOFeAs . Bond charge repulsion and Hund coupling fuse the 2 species of valence bonds into closed strings with a Haldane gap, resulting in a quantum string liquid. A pair of doped holes (electrons) creates an open string and remain at the ends as holon(doublon). Charge -2e spin singlet strings condense to produce high Tc superconductivity. Higher Tc's are likely in our string route to High Tc superconductivity, when competing orders are taken care of.