Evolution of the pseudogap across the magnet-superconductor phase boundary ofNd2−xCexCuO4

Abstract

The doping dependence of electronic states in an electron-doped high-temperature superconductor ͑HTSC͒ Nd 2−x Ce x CuO 4 was studied by high-resolution angle-resolved photoemission spectroscopy. We observed that the high-energy pseudogap around the hot spot shows an abrupt filling-in at the magnet-superconductor phase boundary, resulting in the unusual reconstruction of the Fermi surface. The magnitude ͑⌬ PG ͒ and the temperature ͑T * ͒ at which the pseudogap is filled-in show a close relation to the effective hyperfine coupling energy ͑J eff ͒ and the spin-correlation length ͑ AF ͒, respectively. These results suggest the magnetic origin of the pseudogap and the unconventional nature of the magnet-superconductor phase transition in electron-doped HTSC.

Nernst effect in the electron-doped cuprate superconductorPr2−xCexCuO4: Superconducting fluctuati

“…13, whereby the large hole-like cylinder of the overdoped regime is reconstructed into two small pockets, respectively located at (π, 0) and (π/2, π/2), as the doping is reduced below x 0.16. 43 This reconstruction is consistent with the observation of low-frequency quantum oscillations in (Fig. 12); ν (Fig.…”

“…Sketch of the doping evolution of the Fermi surface in PCCO, based on ARPES measurements performed on NCCO, a closely-related material. 42,43 At high x, in the overdoped regime, the Fermi surface is a single large hole-like nearly circular Fermi cylinder (drawn in red). Below a critical doping xc 0.16, the Fermi surface undergoes a reconstruction, into small hole (red) and electron (blue) pockets.…”

Fermi Surface Reconstruction due to Hidden Rotating Antiferromagnetism in N and P-Type High-TC Cuprates

“…Armitage et al [3] reported ARPES data for n-type material Nd 2−x Ce x CuO 4 , which can be interpreted as revealing the existence of pockets around (π, 0) and symmetric points in the underdoped regime. Also, Matsui et al [22] measured the evolution of the FS with doping for this material using ARPES. A close look at Figure 1 of their work reveals a FS mainly near k-points (π, 0) and (0, π) for doping x = 0.13, but the FS evolves into larger contours joining these two points for the larger doping levels, x = 0.16 and x = 0.17.…”

Nernst effect in the electron-doped cuprate superconductors

“…and parameters t 1 = 0.38 eV, t 2 = 0.32t 1 and t 3 = 0.5t 2 15 , chosen to reproduce the Fermi surface measured in photoemission experiments 7,8 . We will focus on a carrier density corresponding to the electron-doped case, with a two-dimensional density n = 1 + x > 1 per unit cell.…”

“…Indeed, angle resolved photoemission spectroscopy (ARPES) experiments on NCCO found both electron-and hole-like Fermi pockets near optimal doping 7 . In the underdoped region, only small electron-like pockets remain, while in the overdoped region, only a large hole-like pocket centered at (π, π) was found 8 . These features are believed to arise from the commensurate (π, π) SDW order over a wide range of electron doping, as has been detected by various techniques 9,10,11 .…”