Electronic excitations in the antiferromagnetic phase of electron-doped high- Tc cuprates

Abstract

We examine the electronic states of electron-doped cuprates in the underdoped region, and clarify the nature of the antiferromagnetic (AF) phase by using a numerically exact diagonalization technique for the t– t ′– t ″– J model. It is known that a doped electron at half filling in the t– t ′– t ″– J model enters into the k=(π,0) or (0,π) points in the Brillouin zone. From spectral function calculations, we find that doped electrons continue to occupy around (π,0) as long as the AF order persists. Therefore we propose that the AF phase is characterized as an AF state with a small Fermi pocket around (π,0).