标题： 单层$\mathrm{PtTe_2}$中小压缩应变诱导的半导体-金属转变和拉伸应变增强的热电性能 显示英文标题

标题： Small compressive strain induced semiconductor-metal transition and tensile strain enhanced thermoelectric properties in monolayer $\mathrm{PtTe_2}$

摘要： 双轴应变对单层$\mathrm{PtTe_2}$电子结构和热电性能的影响通过使用广义梯度近似（GGA）加上自旋-轨道耦合（SOC）处理电子部分和 GGA 处理声子部分进行研究。 计算结果表明，小的压缩应变（约 -3%）可以引起半导体到金属的转变，这在实验中很容易实现。 观察到未受应变的$\mathrm{PtTe_2}$导带收敛，这种收敛可以通过压缩应变和拉伸应变去除。 拉伸应变可以通过改变价带最大值（VBM）的位置引起价带收敛，这可以产生增强的塞贝克系数，有利于高功率因数。 发现拉伸应变还可以降低晶格热导率，在 4% 的应变下，与室温下的未受应变样品相比可降低约 19%。 考虑到拉伸应变对$ZT_e$和晶格热导率的影响，拉伸应变确实可以提高热电转换的 p 型效率。 我们的结果展示了应变工程在$\mathrm{PtTe_2}$中在电子学和热电应用中的潜力。 显示英文摘要

摘要： Biaxial strain effects on electronic structures and thermoelectric properties of monolayer $\mathrm{PtTe_2}$ are investigated by using generalized gradient approximation (GGA) plus spin-orbit coupling (SOC) for the electron part and GGA for the phonon part. Calculated results show that small compressive strain (about -3\%) can induce semiconductor-to-metal transition, which can easily be achieved in experiment. The conduction bands convergence is observed for unstrained $\mathrm{PtTe_2}$, which can be removed by both compressive and tensile strains. Tensile strain can give rise to valence bands convergence by changing the position of valence band maximum (VBM), which can induce enhanced Seebeck coefficient, being favorable for high power factor. It is found that tensile strain can also reduce lattice thermal conductivity, which at the strain of 4\% can decrease by about 19\% compared to unstrained one at room temperature. By considering tensile strain effects on $ZT_e$ and lattice thermal conductivity, tensile strain indeed can improve p-type efficiency of thermoelectric conversion. Our results demonstrate the potential of strain engineering in $\mathrm{PtTe_2}$ for applications in electronics and thermoelectricity.