The crystal structures of electron-doped cuprates [1].

The high-Tc copper-oxide superconductors (cuprates) break the limit of superconducting transition temperature predicted by the BCS theory based on electron-phonon coupling, thus opens a new chapter in the superconductivity field. According to the valence of substitutes, the cuprates could be categorized into electron- and hole-doped types. Owing to few kinds of electron-doped cuprates and their complicated synthesis procedures, heretofore, researches were addressed rarely on electron-doped counterparts. However, it is undoubtedly that exploring the nature of electron-doped cuprates is indispensable for approaching the mechanism of high-Tc superconductors. Therefore, our group study the properties of electron-doped cuprates Pr₂CuO_4±δ(PCO) films fabricated by polymer assisted deposition method, and La_2-xCe_xCuO_4±δ (LCCO) films fabricated by pulsed laser deposition and high-throughput technique.

A.La_2-xCe_xCuO_4±δ(LCCO)

a.La_2-xCe_xCuO_4±δ single-component films

High quality La_2-xCe_xCuO_4±δ single-crystal films were deposited on SrTiO₃ (STO) substrates by pulsed laser deposition

θ/2θ scan results: only (00l)-oriented peaks of LCCO.

φ scan results: there are four nearly equal peaks

Temperature dependence of resistivity for

La_1.9Ce_0.1CuO_4±δ thin film: Tc0 is ~ 25K

Temperature dependence of resistivity for Temperature dependence of diamagnetism for La_1.9Ce_0.1CuO_4±δ thin film: ΔTc＜1K [2]

b.La_2-xCe_xCuO_4±δ  high-throughput combinatorial films

High quality continuous-gradient-component La_2-xCe_xCuO_4±δ film was deposited on a SrTiO3 (STO) substrate by Laser-MBE

The variation of Ce doping levels with changing the position

in the combinatorial film: the nominal Ce doping changes continuously from 0.1 to 0.19 on a SrTiO₃ substrate [2].

The micro-region XRD θ/2θ scan results (a) and the variation

of c-axis lattice constant with increasing doping levels (b): continuous change of c-lattice constant [3]

(a)The schematic diagram of patterns for electric transport measurements;

(b)doping dependence of Tc0 and Tconset；

(c)the temperature dependence of

resistivity curves at different doping levels: the phase diagram can be obtained efficiently [3].

B.Pr₂CuO_4±δ (PCO)

High-quality superconducting Pr₂CuO_4±δ thin films were grown on SrTiO₃ (STO) substrates by polymer assisted deposition method.

(a) Schematic diagram of polymer assisted deposition method. Metallic ions are represented by red dots and polymeric chains are represented by thick dark lines. Panels (b)–(d) show XRD θ/2θ scans, rocking curve of (006) diffraction peak, and φ scan of the Pr₂CuO_4±δ film on the SrTiO₃ (001) substrate, respectively [4].

Left panel shows the temperature dependence of resistance curves for Pr₂CuO_4±δ thin film at optimal oxygen content [5]: Tc0 is ~ 25K.
Right panel shows the temperature dependence of resistivity curves for Pr₂CuO_4±δ thin films at with different oxygen contents [4]: tunable Tc by controlling the annealing conditions.