Zhang Chunmei, Du Aijun
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus, QLD 4001, Brisbane, Australia.
Beilstein J Nanotechnol. 2018 May 11;9:1399-1404. doi: 10.3762/bjnano.9.132. eCollection 2018.
The cubic ThTaN compound has long been known as a semiconductor with a band gap of approximately 1 eV, but its electronic properties remain largely unexplored. By using density functional theory, we find that the band gap of ThTaN is very sensitive to the hydrostatic pressure/strain. A Dirac cone can emerge around the Γ point with an ultrahigh Fermi velocity at a compressive strain of 8%. Interestingly, the effect of spin-orbital coupling (SOC) is significant, leading to a band gap reduction of 0.26 eV in the ThTaN compound. Moreover, the strong SOC can turn ThTaN into a topological insulator with a large inverted gap up to 0.25 eV, which can be primarily attributed to the inversion between the d-orbital of the heavy element Ta and the p-orbital of N. Our results highlight a new 3D topological insulator with strain-mediated topological transition for potential applications in future spintronics.
立方相ThTaN化合物长期以来被认为是一种带隙约为1 eV的半导体，但其电子性质在很大程度上仍未得到探索。通过使用密度泛函理论，我们发现ThTaN的带隙对静水压力/应变非常敏感。在8%的压缩应变下，狄拉克锥可以在Γ点附近出现，具有超高的费米速度。有趣的是，自旋轨道耦合（SOC）的影响显著，导致ThTaN化合物的带隙减小了0.26 eV。此外，强SOC可以使ThTaN变成一种拓扑绝缘体，其大的反转带隙高达0.25 eV，这主要归因于重元素Ta的d轨道和N的p轨道之间的反转。我们的结果突出了一种新的三维拓扑绝缘体，具有应变介导的拓扑转变，有望在未来的自旋电子学中得到应用。
