论文标题
在高压下，绝缘剂 - 金属渗透导体过渡范德华化合物MEPSE3（ME = Fe，Mn，CD和IN）
Insulator-metal-superconductor transition in medium-entropy van der Waals compound MEPSe3 (ME=Fe, Mn, Cd, and In) under high pressures
论文作者
论文摘要
MPX3（M =金属，X = S或SE）代表了一个大型的范德华（VDW）材料，其p-P二聚体分离为〜2.3Å。它的电运输特性和结构很难通过故意的化学掺杂和离子插入来调节。在这里，我们采用熵增强策略成功地获得一系列中透镜化合物MEPSE3（ME = Fe，MN，CD和IN），其中电气和磁性在其中同时改变了。由于二聚体的解离，p-p-p间距离的伸长率证明了二聚体的单独电子。通过此解离，带隙从0.1 eV扩大到0.7 eV。在高达〜50 GPA的外部物理压力下，C轴上发生了高达15％的巨大崩溃，这与其同行FE/MNPSE3的平面内收缩形成对比。它导致P3-将孤对电子重组成P-P二聚体，而MPX3中28 GPA的最小体积模量最小。 MEPSE3从旋转玻璃绝缘体转移到金属，再到超导体，在MPX3中很少观察到。我们的发现突出了P-P二聚体作为探测各种电子结构的指标以及材料科学中熵增强的有效性。
MPX3 (M=metals, X=S or Se) represents a large family of van der Waals (vdW) materials featuring with P-P dimers of ~2.3 Å separation. Its electrical transport property and structure can hardly be tuned by the intentional chemical doping and ionic intercalation. Here, we employ an entropy-enhancement strategy to successfully obtain a series of medium-entropy compounds MEPSe3 (ME=Fe, Mn, Cd and In), in which the electrical and magnetic properties changed simultaneously. Lone-pair electrons of P emerge due to the dissociation of the dimers as evidenced by a 35% elongation in the P-P interatomic distance. The band gap widens from 0.1 eV to 0.7 eV by this dissociation. Under external physical pressure up to ~50 GPa, a giant collapse of up to 15% in the c-axis happens, which is in contrast to the in-plane shrinkage of their counterparts Fe/MnPSe3. It leads to the recombination of P3- with lone pair electrons into a P-P dimer and the smallest bulk modulus of 28 GPa in MPX3. The MEPSe3 transits from a spin-glass insulator to metal, and to superconductor, which is rarely observed in the MPX3. Our findings highlight the P-P dimer as an indicator to probe diverse electronic structure and the effectiveness of entropy-enhancement in materials science.
