paper

Suppression of the antiferromagnetic pseudogap in the electron-doped high-temperature superconductor by "protect annealing"

arXiv:1502.03395 · doi:10.1038/ncomms10567

Abstract

In the hole-doped cuprates, a small amount of carriers suppresses antiferromagnetism and induces superconductivity. In the electron-doped cuprates, on the other hand, superconductivity appears only in a narrow range of high electron concentration ( $\sim$ doped Ce content) after reduction annealing, and strong antiferromagnetic (AFM) correlation persists in the superconducting phase. Recently, Pr $_{1.3 - x}$ La $_{0.7}$ Ce $_{x}$ CuO $_{4}$ (PLCCO) bulk single crystals annealed by a "protect annealing" method showed a high $T_{c}$ of $\sim$ 27 K for small Ce content down to $x \sim 0.05$ . By angle-resolved photoemission spectroscopy (ARPES) measurements of PLCCO crystals, we observed a sharp quasi-particle peak on the entire Fermi surface without signature of an AFM pseudogap unlike all the previous work, indicating a dramatic reduction of AFM correlation length and/or of magnetic moments. The superconducting state was found to extend over a wide electron concentration range. The present ARPES results fundamentally change the long-standing picture on the electronic structure in the electron-doped regime.

23 pages, 7 figures