Rout Paresh C, Schwingenschlögl Udo
Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
Adv Sci (Weinh). 2022 Sep;9(26):e2106037. doi: 10.1002/advs.202106037. Epub 2022 Jul 21.
The influence of epitaxial strain on the electronic, magnetic, and optical properties of the distorted double perovskite Ca FeOsO is studied. These calculations show that the compound realizes a monoclinic structure with P2 /n space group from -6% to +6% strain. While it retains ferrimagnetic ordering with a net magnetic moment of 2 μ per formula unit at low strain, it undergoes transitions into E-antiferromagnetic and C-antiferromagnetic phases at -5% and +5% strain, respectively. It is shown that spin frustration reduces the critical temperature of the ferrimagnetic ordering from the mean field value of 600-350 K, in excellent agreement with the experimental value of 320 K. It is also shown that the critical temperature can be tuned efficiently through strain and that the spin coherence length surpasses that of Sr FeMoO under tensile strain. An indirect-to-direct bandgap transition is observed at +5% strain. Localization of the valence and conduction states on different transition metal sublattices enables efficient electron-hole separation upon photoexcitation. The calculated spectroscopic limited maximum efficiency of up to 33% points to excellent potential of Ca FeOsO in solar cell applications.
研究了外延应变对畸变双钙钛矿CaFeOsO的电子、磁性和光学性质的影响。这些计算表明，该化合物在-6%至+6%的应变范围内实现了具有P2 /n空间群的单斜结构。在低应变下，它保持亚铁磁有序，每个化学式单位的净磁矩为2 μ，而在-5%和+5%的应变下，分别转变为E型反铁磁相和C型反铁磁相。结果表明，自旋阻挫将亚铁磁有序的临界温度从平均场值600 - 350 K降低，这与320 K的实验值非常吻合。还表明，临界温度可以通过应变有效地调节，并且在拉伸应变下，自旋相干长度超过了SrFeMoO的自旋相干长度。在+5%的应变下观察到间接带隙到直接带隙的转变。价态和导带态在不同过渡金属亚晶格上的局域化使得光激发时能够实现有效的电子-空穴分离。计算得出的高达33%的光谱极限最大效率表明CaFeOsO在太阳能电池应用中具有优异的潜力。
