论文标题
MGB2薄膜的超导特性上的双轴应变工程
Biaxial strain engineering on the superconducting properties of MgB2 thin film
论文作者
论文摘要
通过第一原理计算研究了双轴应变对MGB2薄膜超导性能的影响。通过声子分散剂进行的稳定性分析表明，双轴菌株可以将多达7％应用于MGB2上，而无需诱导任何假想的频率。基于Migdal-Eliashberg理论框架的超导性能计算成功地再现了MGB2的两间隙超导性。结果表明，拉伸双轴应变可以增加MGB2的临界温度，而压缩双轴应变会降低临界温度。通过计算电子结构和声子分散剂，研究了双轴应变效应对超导特性的详细微观机制。增加的TC是在费米水平和面内硼声子软化下电子密度增加的结合结果。通过对适当底物的高通量筛选，发现大多数底物会导致MGB2膜中的拉伸应变，这与许多实验性工作一致。这项工作的结果提供了对双轴应变工程机制的详细了解，并证明双轴应变工程可以是调整MGB2和其他类似材料的超导性能的有效方法。
The effect of biaxial strain on the superconducting properties of MgB2 thin films was studied by first-principles calculations. The stability analyses by phonon dispersions show that biaxial strain as much as 7% can be applied onto MgB2 without inducing any imaginary frequency. The superconducting property calculations based on the frame of Migdal-Eliashberg theory successfully reproduce the two-gap superconductivity of MgB2. The results show that the tensile biaxial strain can increase the critical temperature of MgB2 while the compressive biaxial strain would decrease the critical temperature. The detailed microscopic mechanism of the biaxial strain effect on the superconducting properties was studied by calculations of electronic structures and phonon dispersions. The increased Tc is a combining result of the increased electron density at the Fermi level and the in-plane boron phonon softening. By means of high-throughput screening of proper substrates, it is found that most of the substrates would result in tensile strain in MgB2 film, which is in agreement with many experimental works. The results in this work provide detailed understanding of the biaxial strain engineering mechanism and demonstrate that biaxial strain engineering can be an effective way of tuning the superconducting properties of MgB2 and other similar materials.
