Enhanced superconductivity in few-layer TaS2 due to healing by oxygenation.
Enhanced superconductivity in few-layer TaS2 due to healing by oxygenation.
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DOI：
10.1021/acs.nanolett.0c00871
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发表时间：
2019-12
期刊：
影响因子：
10.8
通讯作者：
J. Bekaert;E. Khestanova;D. Hopkinson;J. Birkbeck;Nick Clark;Mengjian Zhu;D. Bandurin;R. Gorbachev;S. Fairclough;Yichao Zou;M. Hamer;D. Terry;J. J. Peters-J.;A. Sánchez;B. Partoens;S. Haigh;M. Milošević;I. Grigorieva
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文献类型：
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作者：
J. Bekaert;E. Khestanova;D. Hopkinson;J. Birkbeck;Nick Clark;Mengjian Zhu;D. Bandurin;R. Gorbachev;S. Fairclough;Yichao Zou;M. Hamer;D. Terry;J. J. Peters-J.;A. Sánchez;B. Partoens;S. Haigh;M. Milošević;I. Grigorieva
当接近原子薄极限时，缺陷和无序对二维材料的性能起着越来越重要的作用。虽然缺陷通常被认为对二维材料的超导性有负面影响，但在超薄二硫化钽（TaS2）的氧化情况下，我们证明了相反的情况。我们的第一性原理计算表明，将氧结合到TaS2晶格中在能量上是有利的，并且有效地修复了这些晶体中通常存在的硫空位，从而恢复了电子能带结构和载流子密度到TaS2的固有特征。引人注目的是，这导致电子-声子耦合的强烈增强，在高氧极限下高达80%。通过对新鲜和老化（氧化）的少层TaS2的输运测量，我们发现在老化过程中超导临界温度（Tc）显着增加，与我们的理论一致，同时电子显微镜和电子能量损失谱证实了新鲜制备的TaS2中存在硫空位，并且随着时间的推移，氧进入晶格。因此，我们的工作揭示了某些原子尺度缺陷可能有利于超导性的机制，并为超薄材料中的Tc工程开辟了新的途径。
When approaching the atomically thin limit, defects and disorder play an increasingly important role in the properties of two-dimensional materials. While defects are generally thought to negatively affect superconductivity in 2D materials, here we demonstrate the contrary in the case of oxygenation of ultrathin tantalum disulfide (TaS2). Our first-principles calculations show that incorporation of oxygen into the TaS2 crystal lattice is energetically favourable and effectively heals sulfur vacancies typically present in these crystals, thus restoring the electronic band structure and the carrier density to the intrinsic characteristics of TaS2. Strikingly, this leads to a strong enhancement of the electron-phonon coupling, by up to 80% in the highly-oxygenated limit. Using transport measurements on fresh and aged (oxygenated) few-layer TaS2, we found a marked increase of the superconducting critical temperature (Tc) upon aging, in agreement with our theory, while concurrent electron microscopy and electron-energy loss spectroscopy confirmed the presence of sulfur vacancies in freshly prepared TaS2 and incorporation of oxygen into the crystal lattice with time. Our work thus reveals the mechanism by which certain atomic-scale defects can be beneficial to superconductivity and opens a new route to engineer Tc in ultrathin materials.