应力对5d过渡金属氧化物NaOsO₃的电子结构的影响的理论研究

The Strain Effect on the Band Gap of NaOsO₃: First-Principles Study

摘要: 研究应力作用下材料的物理性质特别是电子结构性质对发掘材料的应用价值具有重要的指导作用。我们通过第一性原理计算方法，研究了应力作用下5d过渡金属氧化物NaOsO3的电子结构和磁学性质。我们发现对NaOsO₃施加压缩应力时，NaOsO₃的带隙出现反常的变化趋势，即随着压缩应力的增加，其带隙减小。分析不同应力下的电子结构发现，布里渊区不同区域对应力的响应不同。这种不同的响应是因为其不同的波函数构成所导致。当波函数为Os-d_xy与O-p杂化的成键态时，其决定的能隙随应力增加而减小；反之，当波函数为Os-d_xz/yz与O-p杂化的反键态，其决定的能隙随应力增加而增加。这种电子结构对应力的奇特的响应可能在将来的电子器件中有应用前景。

Abstract: Exploring the physical properties of materials under external strain is crucial for the development of their potential applications. Through first-principles calculations, we studied the effect of exter-nal strain on the electronic and magnetic properties of NaOsO₃. We found that the band gap of Na-OsO₃ shows abnormal behavior under compressive strain. the band gap decreases as the compres-sive strain increases. Analysis of the electronic structures reveals that different regions in the Bril-louin zone have different responses to the external strain, because of the corresponding different wavefunctions. For the places contributed from the bonding states of the hybridization between Os-d_xy and O-p orbitals, the band gap decreases as the external strain increases; while for the plac-es contributed from the antibonding states of the hybridization between Os-d_xz/yz and O-p orbitals, the band gap increases as the external strain increases. This intriguing feature of the band gap is of potential applications in the future electronic devices.