Open AccessLarge Spin Coherence Length and High Photovoltaic Efficiency of the Room Temperature Ferrimagnet Ca 2 FeOsO 6 by Strain Engineering
Author(s) -
Rout Paresh C.,
Schwingenschlögl Udo
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202106037
Subject(s) - ferrimagnetism , condensed matter physics , antiferromagnetism , materials science , coherence length , monoclinic crystal system , strain engineering , band gap , crystallography , magnetization , chemistry , magnetic field , phase transition , physics , crystal structure , superconductivity , quantum mechanics
Abstract The influence of epitaxial strain on the electronic, magnetic, and optical properties of the distorted double perovskite Ca 2 FeOsO 6 is studied. These calculations show that the compound realizes a monoclinic structure with P 2 1 / n space group from −6% to +6% strain. While it retains ferrimagnetic ordering with a net magnetic moment of 2 μ B 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 2 FeMoO 6 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 2 FeOsO 6 in solar cell applications.