论文标题
调整化学计量及其对单层和多层FESE超导的影响SRTIO3
Tuning stoichiometry and its impact on superconductivity of monolayer and multilayer FeSe on SrTiO3
论文作者
论文摘要
与散装FESE相比，SRTIO3上单层FESE的合成具有很大的增强。始终需要在某个温度窗口内进行冗长的退火，以实现全球不同组报告的超导样本，但是尚未阐明退火的机制。我们通过分子束外延在SRTIO3上生长FESE膜，并通过沉积其他少量的Fe原子来调节化学计量。单层膜在FE沉积后变为超导，而无需退火，并显示出与传输测量中退火膜的过渡温度相似的过渡温度。我们还在5个单元的膜上证明了FESE多层可以在非驱动导向$ \ sqrt {5} \ times \ times \ sqrt {5} $相位之间进行可逆调节，并带有fe-vacancies和超导能力和超导$ 1 \ $ 1 \ times 1 $。我们的结果表明，传统的退火过程本质上消除了FE空缺，而额外的FE沉积是实现超导性的更有效方法。这项工作突出了化学计量在FESE薄膜的超导性中的重要性，并为超导样品提供了简单的途径。
Synthesis of monolayer FeSe on SrTiO3, with greatly enhanced superconductivity compared to bulk FeSe, remains difficult. Lengthy annealing within a certain temperature window is always required to achieve superconducting samples as reported by different groups around the world, but the mechanism of annealing in inducing superconductivity has not been elucidated. We grow FeSe films on SrTiO3 by molecular beam epitaxy and adjust the stoichiometry by depositing additional small amounts of Fe atoms. The monolayer films become superconducting after the Fe deposition without any annealing, and show similar superconducting transition temperatures as those of the annealed films in transport measurements. We also demonstrate on the 5-unit-cell films that the FeSe multilayer can be reversibly tuned between the non-superconducting $\sqrt{5} \times \sqrt{5}$ phase with Fe-vacancies and superconducting $1 \times 1$ phase. Our results reveal that the traditional anneal process in essence removes Fe vacancies and the additional Fe deposition serves as a more efficient way to achieve superconductivity. This work highlights the significance of stoichiometry in the superconductivity of FeSe thin films and provides an easy path for superconducting samples.
