Effects of occupation-numbers in (3d–5d) and U energy on transport and magnetic properties of complex perovskites Pb₂MReO₆ (M = Cr, Mn and Fe) by LSDA and LSDA + U methods

Graphical abstract: Schematic illustration of the ferrimagnetic ordering between M (3d) and Re (5d) ions, the spin on Cr³⁺ (S = 3/2) – Re⁵⁺ (S = 1), Mn²⁺ (S = 5/2) – Re⁶⁺ (S = 1/2) and Fe³⁺ (S = 5/2) – Re⁵⁺ (S = 1) interacted antiferromagnetically by a strong super-exchange interaction through the O²⁻ ligands, M↑–O–Re↓, resulting in spontaneous magnetization. Small black bars inside the spheres represent the levels of the 3d and 5d orbitals on M (3d) and Re (5d) ions. Up and down arrows represent the spin-direction on M (3d) and Re (5d) ions. - Highlights: • Series of complex perovskites Pb₂MReO₆ (M = Cr, Mn and Fe) have been investigated. • The occupation-numbers in M (3dⁿ)–Re (5d^m) influenced the physical properties. • Pb₂MReO₆ stabilized in tetragonal crystal (space group I4/m); (a⁰a⁰c⁻) tilt-system. • LSDA + U calculations produced ferrimagnetic half-metallic in all compounds. - Abstract: Three compounds of lead-based complex perovskites Pb₂MReO₆ (M = Cr, Mn and Fe) have been investigated in detail based on density functional theory (DFT) using local spin density approximation (LSDA) and (LSDA + U) methods. By introducing a series of 3d-ions in M-site, the number of valence electrons that occupied the 3d-orbitals can be increased from Cr³⁺(3d³) to Mn²⁺(3d⁵) and Fe³⁺(3d⁵), and this beside the effect of energy U are the main factors that influenced the physical properties of Pb₂MReO₆. Magnetic and electronic calculations showed that all Pb₂MReO₆ compounds have ferrimagnetic half-metallic (FI-HM) properties. FI-HM are attributed to the M (3d)–Re (5d) hybridization through the strong 180° super-exchange (SE) interaction via the long-range pathway M (3d)↑–O (2p)–Re (5d)↓, in conformity with both Pauli Exclusion principles and Goodenough-Kanamori rules. This result is interpreted within a scenario where the Re (5d) states play a crucial role in the FI-HM ground state.