GAUGE THEORY FOR A DOPED ANTIFERROMAGNET IN A ROTATING REFERENCE-FRAME

Abstract

We study the consequences of hole-doping in a two-dimensional spin- ½ quantum antiferromagnet. The analysis of a U(1) gauge theory that describes the system in a rotating reference-frame, where the spin-quantization axis of the fermions follow the local order-parameter of the antiferromagnet, leads to a quantitative description of the transition from a Néel ordered to a quantum disordered (QD) spin-liquid phase. Furthermore, it is shown that the spontaneously generated gap in the spin-wave excitation spectrum defines a new energy scale, which determines the strength of an attractive long-range interaction between magnetic and fermionic excitations. The possible bound-states are singlet objects that correspond to the phenomena of charge-spin separation and pairing. Therefore, a close connection between these phenomena and the opening of the spin-gap is revealed.