Stable large half-metallic energy-gap, high thermoelectric performance, and enhanced Tc in LaMn3Ru2M2O12 (M = Mn and Fe): Strain modulations

초록

We report on the various aspects of the newly discovered M = Mn-/Fe-doped (dop.) LaMn3Ru2M2O12 quadrupole double perovskite oxide (QDPO) under stain effects using ab-initio calculation. Electronically, unstrained Mn-/Fe-dop. motif showing a semiconducting (SC) behavior with an Eg of 0.06/0.84 eV holding a Curie temperature (temp.) of 253/266 K. The calculated spin magnetic moment (ms) on the Mn3+/Ru3+/Fe3+ ion along with three-dimensional (3D) isosurfaces, confirms the ferrimagnetic (FiM) state owing Mn3+up arrow- Mn3+ down arrow/Ru3+ up arrow-Ru3+ down arrow/Fe3+up arrow-Fe3+down arrow spin ordering with S = 2/12/52. Due to a good SC nature, Fe-dop. motif exhibits a high figure of merit (ZT) of 0.77/0.84 at 300/750 K compared to Mn-dop. of 0.31/0.38. Strikingly, a half-metallic (HM) state in the Mn-dop. system emerges at a critical (criti.) biaxial ([110]) tensile strain of + 2% having an Eg of 1.14 eV in the non-metallic channel that is highly sufficient to prevent spin-flipping as well as to provide a long mean free path for spin and stability against thermal excitation. However, a sharp decrease in ZT value at 300 K is predicted in the Mn-dop. motif at a criti. +2% tens. strain due to an electronic transition from SC to HM phase. Conversely, Fe-dop. system sustains its SC nature under all strain (-5% to + 5%) levels. Along with this, Tcgrows to 32/12% and 28/12% K for compressive (-5%)/tensile (+5%) strain in the Mn and Fe-dop. motif, respectively. Hence, the recent work has a significant role in gaining a deep understanding of QDPO, which promises probable applications in spintronic applications and thermoelectric devices.

키워드