Abstract
In this study, motivated by observations of the remarkable magnetic insulating nature and high Curie temperature (TC=725K) of double perovskite oxide Sr2CrOsO6, the electronic, magnetic, and optical characteristics of Sr2CrOsO6 were determined using the full potential linear muffin-tin orbital method according to density functional theory. The spin-orbit coupling contribution was included in the local spin density approximation (LSDA) and generalized gradient approximation (GGA). In addition, the Coulomb repulsion (U) and Hund’s exchange (J) energies were considered in both methods (LSDA+U and GGA+U). Full structural optimization confirmed that the ground state of Sr2CrOsO6 is face-centered cubic (Fm-3m symmetry). Calculations predicted that Sr2CrOsO6 is ferrimagnetic half-semiconductive (HSC) due to the vertical hopping of t2g electrons via antiferromagnetic coupling [Cr3+ (t2g3↑)–O (2pπ)–Os5+ (t2g3↓)], which agreed with the experimental results. The HSC energy-gaps originate from the splitting of three partially occupied Os5+ (5d) bands into two fully filled bands and one empty spin-down band. The real ε1(ω) and imaginary ε2(ω) parts of the dielectric function ε(ω) and energy-loss spectrum L(ω) were calculated, analyzed, and compared with the electronic results.
Fig. 6. The optical spectra of the imaginary (Im.) part (black curve), real (Re.) part (red curve) of the dielectric function ε(ω), and the electron energy loss spectra L(ω) (blue curve) for the cubic Sr2CrOsO6, from LSDA, LSDA+SOC, LSDA+U and (LSDA+U)+SOC calculations.
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•LSDA (GGA)+U+SOC methods are considered for Sr2CrOsO6.•The magnetic and optical properties of Sr2CrOsO6 are calculated and analyzed.•AFM super-exchange interaction is used to explain magnetic coupling.