Multifunctional materials with outstanding performance have enormous potential applications in the next generation of nanodevices. Using first principles calculations, we design a series of multifunctional two-dimensional materials in monolayer α_nh_m-GeSe (n, m = 1, 2) that combine auxeticity and piezoelectricity. Due to the similar local structures of α-GeSe and h-GeSe, monolayer α_nh_m-GeSe can be designed through the combination of these two materials. Elastic constants and phonon dispersion curves confirm that all the structures are mechanically and dynamically stable. Monolayer α_nh_m-GeSe exhibits auxetic properties with an in-plane negative Poisson's ratio along the diagonal direction. An out-of-plane negative Poisson's ratio effect can be observed by applying tensile strain in the x-direction, which is beneficial for mechanical devices. Only a few materials are both in-plane and out-of-plane auxetic. In addition, monolayer α_nh_m-GeSe can exhibit electric polarization because of the breaking of the central symmetry, demonstrating in-plane piezoelectric properties with strong anisotropy. The above results make monolayer α_nh_m-GeSe an interesting multifunctional material and provide a candidate material for a nanoscale device.

中文翻译：

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αnhm-GeSe：一种结合了增光性和压电性的多功能半导体


具有出色性能的多功能材料在下一代纳米器件中具有巨大的潜在应用。使用第一性原理计算，我们设计了一系列单层 α_nh_m-GeSe （n， m = 1， 2） 的多功能二维材料，它们结合了生长性和压电性。由于 α-GeSe 和 h-GeSe 的局部结构相似，因此可以通过这两种材料的组合来设计单层 α_nh_m-GeSe。弹性常数和声子色散曲线证实，所有结构在机械和动态上都是稳定的。单层 α_nh_m-GeSe 表现出生长特性，沿对角线方向具有面内负泊松比。通过在 x 方向上施加拉伸应变，可以观察到面外负泊松比效应，这对机械设备有利。只有少数材料既是面内又是面外的增效材料。此外，由于中心对称性的打破，单层 α_nh_m-GeSe 可以表现出极化，表现出具有强各向异性的面内压电特性。以上结果使单层 α_nh_m-GeSe 成为一种有趣的多功能材料，并为纳米级器件提供了一种候选材料。