Emergent layered Cu-bearing van der Waals (vdW) compounds have great potentials for use in electrocatalysis, lithium batteries, and electronic and optoelectronic devices. However, many of their alluring properties such as potential superconductivity remain unknown. In this work, using CuP₂Se as a model compound, we explored its electrical transport and structural evolution at pressures up to ∼60 GPa using both experimental determinations and ab initio calculations. We found that CuP₂Se undergoes a semiconductor-to-metal transition at ∼20 GPa at room temperature and a metal-to-superconductor transition at 3.3–5.7 K in the pressure range from 27.0 to 61.4 GPa. At ∼10 and 20 GPa, there are two isostructural changes in the compound, corresponding to, respectively, the emergence of the interlayer coupling and start of interlayer atomic bonding. At a pressure between 35 and 40 GPa, the vdW layers start to slide and then merge, forming a new phase with high coordination numbers. We also found that the Bardeen–Cooper–Schrieffer (BCS) theory describes quite well the pressure dependence of the critical temperature despite occurrence of a possible medium-to-strong electron–phonon coupling, revealing the determinant roles of the enhanced bulk modulus and electron density of states at high pressure. Moreover, nanosizing of CuP₂Se at high pressure further increased the critical temperature even at sizes approaching the Anderson limit. These findings would have important implications for developing novel applications of layered vdW compounds through simple pressure tuning of the interlayer coupling.

中文翻译：

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通过层间耦合的压力调节在范德华化合物 CuP2Se 中的金属化和超导性

新兴的层状含铜范德华 (vdW) 化合物在电催化、锂电池以及电子和光电器件中具有巨大的应用潜力。然而，它们的许多诱人特性如潜在的超导性仍然未知。在这项工作中，我们使用 CuP ₂ Se 作为模型化合物，使用实验测定和从头计算，探索了其在高达 60 GPa 压力下的电输运和结构演变。我们发现 CuP ₂Se 在室温下在~20 GPa 下经历半导体到金属的转变，在 27.0 到 61.4 GPa 的压力范围内在 3.3–5.7 K 下经历金属到超导体的转变。在~10 GPa 和 20 GPa 时，化合物有两种同构变化，分别对应于层间耦合的出现和层间原子键的开始。在 35 到 40 GPa 之间的压力下，vdW 层开始滑动然后合并，形成具有高配位数的新相。我们还发现 Bardeen-Cooper-Schrieffer (BCS) 理论很好地描述了临界温度的压力依赖性，尽管可能发生了中强电子-声子耦合，揭示了增强的体积模量和电子的决定性作用高压下的态密度。此外，CuP 的纳米尺寸即使尺寸接近安德森极限，高压下的₂ Se 也进一步提高了临界温度。这些发现将对通过层间耦合的简单压力调整开发层状 vdW 化合物的新应用具有重要意义。