Spinon excitation spectra of the resonating valence bond states in the high temperature superconducting cuprates

Abstract

Magnetic excitations of the resonating valence bond (RVB) states were searched in high temperature superconducting cuprates by Raman scattering. Ho et al. [C.-M. Ho et al., Phys. Rev. Lett. 86 (2001) 1626] disclosed that the spin excitation in the two-dimensional resonating valence bond state has a magnon-like dispersion and a spinon continuum above it. The density of states of the spin excitation has a peak at 1.5J which is lower than the 2.36J of the spin wave. We found that the A1g spectra have a broad peak at 1.5J in common at the underdoped region of p⩽0.15 in LSCO, Bi2201, and Bi2212 and p⩽0.1 in YBCO. The B1g peak and the B2g peak in the two-magnon region have a fine structure of the spin wave. The carrier density dependence is discussed.