Structural, electronic and magnetic properties of the double perovskite Ba₂GdNbO₆ with octahedral tilting effect: first-principles calculations

ABSTRACT

In this research, we are interested to study the physical properties of the double perovskite oxide Ba₂GdNbO₆ under the effect of octahedral tilting, where this material crystallises in the tetragonal structure (I4/m (no. 87), Z = 2). The structural, electronic and magnetic properties are investigated using the spin-polarised density functional theory within the framework of the GGA + U approximation. The structural stability for Ba₂GdNbO₆ compound has been verified; this shows that I4/m structure is reported as stable ground state of Ba₂GdNbO₆ compound. The phenomenon of octahedral tilting contributes to the stability of this material and to the apparition of the quantum aspect. The X-spectra study show that the structural transition can occur between the I4/m symmetry system (the stable ground state) and the Fm$\overline{3}m$ symmetry system (the excited state), the absorbed radiation of this structural transition corresponds to the Middle-Wave-Infrared (MWIR). The electronic structure of Ba₂GdNbO₆ compound has been investigated in the stable ground state; the results show that the octahedral Ba₂GdNbO₆ compound has semiconductor behaviour with an indirect band gap. The results of total and partial spin-magnetic moments of Ba₂GdNbO₆ compound show that the main contribution to the total magnetic moment comes from the Gd ion, it is obvious to note that the half-filled in Gd (4f⁷) orbital is responsible for the semiconductor behaviour. Moreover, the GGA + U approximation supported by QTL programme shows that the multiplicity in the occupied 4f-Gd states is corresponding to the lower energy level of (⁸$S_{\left(\frac{7}{2}\right)\uparrow }$).

KEYWORDS:

• Double perovskite
• infrared absorption
• DFT
• band structures
• QTL programme
• magnetic moments

Acknowledgements

This research project (for Amel Laref) was supported by a grant from the ‘Research centre of the Female Scientific and Medical Colleges’, Deanship of Scientific Research, King Saud University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The present work is supported by the Algerian National Scientific Research Agency's University Training Research Projects (PRFU) [grant number B00L02UN290120220002].