Batool Javaria, Alay-E-Abbas Syed Muhammad, Johansson Gustav, Zulfiqar Waqas, Danish Muhammad Arsam, Bilal Muhammad, Larsson J Andreas, Amin Nasir
Computational Materials Modeling Laboratory, Department of Physics, Government College University Faisalabad, 38040 Faisalabad, Pakistan.
Department of Physics, Government College Women University Faisalabad, Faisalabad, Pakistan.
Phys Chem Chem Phys. 2021 Nov 10;23(43):24878-24891. doi: 10.1039/d1cp03989j.
The thermodynamic, structural, magnetic and electronic properties of the pristine and intrinsic vacancy-defect-containing topological Dirac semimetal BaSnO are studied using first-principles density functional theory calculations. The thermodynamic stability of BaSnO has been evaluated with reference to its competing binary phases BaSn, BaSn and BaO. Subsequently, valid limits of the atomic chemical potentials derived from the thermodynamic stability were used for assessing the formation of Ba, Sn and O vacancy defects in BaSnO under different synthesis environments. Based on the calculated defect-formation energies, we find that the charge-neutral oxygen vacancies are the most favourable type of vacancy defect under most chemical environments. The calculated electronic properties of pristine BaSnO show that inclusion of spin-orbit coupling in exchange-correlation potentials computed using generalized gradient approximation yields a semimetallic band structure exhibiting twin Dirac cones along the - path of the Brillouin zone. The effect of spin-polarization and spin-orbit coupling on the physical properties of intrinsic vacancy defects containing BaSnO has been examined in detail. Using Bader charges, electron localization function (ELF), electronic density of states (DOS) and spin density, we show that the isolated oxygen vacancy is a magnetic defect in anti-perovskite BaSnO. Our results show that the origin of magnetism in BaSnO is the accumulation of unpaired charges at the oxygen vacancy sites, which couple strongly with the 5d states of the Ba atom. Owing to the metastability observed in earlier theoretically predicted magnetic topological semimetals, the present study reveals the important role of intrinsic vacancy defects in giving rise to magnetism and also provides opportunities for engineering the electronic structure of a Dirac semimetal.
采用第一性原理密度泛函理论计算方法，研究了原始的以及含有本征空位缺陷的拓扑狄拉克半金属BaSnO的热力学、结构、磁性和电子性质。参照其竞争二元相BaSn、BaSn和BaO，评估了BaSnO的热力学稳定性。随后，利用由热力学稳定性导出的原子化学势的有效极限，评估了在不同合成环境下BaSnO中Ba、Sn和O空位缺陷的形成情况。基于计算得到的缺陷形成能，我们发现电荷中性的氧空位是大多数化学环境下最有利的空位缺陷类型。计算得到的原始BaSnO的电子性质表明，在使用广义梯度近似计算的交换关联势中包含自旋轨道耦合，会产生一种半金属能带结构，在布里渊区的 - 路径上呈现双狄拉克锥。详细研究了自旋极化和自旋轨道耦合对含有BaSnO的本征空位缺陷物理性质的影响。利用巴德电荷、电子定域函数（ELF）、电子态密度（DOS）和自旋密度，我们表明孤立的氧空位是反钙钛矿BaSnO中的磁性缺陷。我们的结果表明，BaSnO中磁性的起源是氧空位处未配对电荷的积累，这些电荷与Ba原子的5d态强烈耦合。由于在早期理论预测的磁性拓扑半金属中观察到的亚稳性，本研究揭示了本征空位缺陷在产生磁性方面的重要作用，也为设计狄拉克半金属的电子结构提供了机会。
