C. Kubert et A. Muramatsu, GAUGE-THEORY FOR A DOPED ANTIFERROMAGNET IN A ROTATING REFERENCE-FRAME, International journal of modern physics b, 10(28), 1996, pp. 3807-3826
We study the consequences of hole-doping in a two-dimensional spin-1/2
quantum antiferromagnet. The analysis of a U(1) gauge theory that des
cribes the system in a rotating reference-frame, where the spin-quanti
zation axis of the fermions follow the local order-parameter of the an
tiferromagnet, leads to a quantitative description of the transition f
rom a Neel ordered to a quantum disordered (QD) spin-liquid phase. Fur
thermore, 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 obje
cts that correspond to the phenomena of charge-spin separation and pai
ring. Therefore, a close connection between these phenomena and the op
ening of the spin-gap is revealed.