The phase diagram of electron-doped La2−xCexCuO4−δ

Abstract

Superconductivity is a striking example of a quantum phenomenon in which electrons move coherently over macroscopic distances without scattering. The high-temperature superconducting oxides (cuprates) are the most studied class of superconductors, composed of two-dimensional CuO 2 planes separated by other layers that control the electron concentration in the planes. A key unresolved issue in cuprates is the relationship between superconductivity and magnetism. Here we report a sharp phase boundary of static threedimensional magnetic order in the electron-doped superconductor La 2 À x Ce x CuO 4 À d , where small changes in doping or depth from the surface switch the material from superconducting to magnetic. Using low-energy spin-polarized muons, we find that static magnetism disappears close to where superconductivity begins and well below the doping level at which dramatic changes in the transport properties are reported. These results indicate a higher degree of symmetry between the electron and hole-doped cuprates than previously thought.

Doping-dependent charge order correlations in electron-doped cuprates

“…The T c was typically 20 ± 1 K. As typical, the normal-state resistivity (in a field above H c2 ) shows a low-temperature upturn. These LCCO films are similar to those prepared for other experiments by the Maryland group ( 44 ). Further details can be found in the Supplementary Materials.…”

DMFT Study on the Electron–hole Asymmetry of the Electron Correlation Strength in the High Tc Cuprates

“…However, recent experimental studies have shown that, in the electron-doped systems, the electron correlation strength is not so strong that even very lightly doped samples exhibit superconductivity if they are properly annealed and the antiferromagnetism is suppressed. Some of these studies suggest that superconductivity persists even with no electron doping, [1][2][3] while others show presence of antiferromagnetic long range order in the lightly doped regime, 4,5) so that the issue is still controversial. It was also shown experimentally that the "pseudo gap", [6][7][8][9][10] a prominent feature of the cuprates, disappears if the antiferromagnetism is suppressed.…”

Shubnikov-de Haas quantum oscillations reveal a reconstructed Fermi surface near optimal doping in a thin film of the cuprate superconductorPr1.86Ce0.14CuO4±δ

“…Photoemission (ARPES) experiments are consistent with a large FS in overdoped n-doped materials [10][11][12], and show evidence for both electron-and hole-like pockets as x decreases below ∼ 0.16. However, many issues remain unresolved, including the structure of the FS and nature of its reconstruction and evolution with doping, reconciling quantum oscillation measurements with the observation of Fermi arcs [13,14] in the pseudogap phase, and identifying the true nature of the competing ground state (whether arising from observed magnetic [15,16] …”

“…Photoemission (ARPES) experiments are consistent with a large FS in overdoped n-doped materials [10][11][12], and show evidence for both electron-and hole-like pockets as x decreases below ∼ 0.16. However, many issues remain unresolved, including the structure of the FS and nature of its reconstruction and evolution with doping, reconciling quantum oscillation measurements with the observation of Fermi arcs [13,14] in the pseudogap phase, and identifying the true nature of the competing ground state (whether arising from observed magnetic [15,16] charge [17], or predicted d-density wave (DDW) [18]) order). QO have only been observed in a restricted doping range (x = 0.15 -0.17) in n-doped bulk crystals of Nd 2−x Ce x CuO 4 (NCCO) [19][20][21], and found to be consistent with a theoretical picture of DDW-like order [22,23].…”