Giant magnetic anisotropy energy and Os–Ir coupling driven variations in the physical properties of Y[formula omitted]NiIrO[formula omitted

Abstract

Spintronics is a prosperous domain that comprises colossal applications executing both the charge and spin of the electrons. So double perovskite oxides (DPO) having unusual magnetism are very relevant for these objectives. Therefore, we systematically examine the effect of strong coupling between Ir and Os 5d orbitals on the structural stabilities, electronic structure, and magnetic properties of the Y2NiIrO6 DPO using ab-initio calculations by replacing Os with one of the Ir ion (Os@Ir). We predict that the antiferromagnetic spin–orbit coupling between half-filled Ni 3d and partially-filled Ir 5d in the pristine structure, results in a ferrimagnetic (FiM) Mott-insulating phase due to unusual Jeff=12 state of Ir+4 having an energy band gap (Eg) of 0.43 eV. The calculated partial spin moments (ms) on the Ni+2 and Ir+4 ions are 1.68 and −0.49μB with electronic configurations of t2g3↑t2g3↓eg2↑eg0↓ (S = 1) and t2g3↑t2g2↓eg0 (S =12), respectively. Furthermore, our estimated Curie temperature (TC) of 198 K employing the Heisenberg model is near to the experimentally examined value of 192 K. The easy magnetic axis yields to be the b-axis with a giant magnetocrystalline anisotropy energy (MAE) constant of 1.7×108 erg/cm3, which is the origin of a huge coercive field of 1.1 T. In the case of the Os@Ir motif, Eg closed where the filled Ir t2g and partially filled Os t2g orbitals are mainly responsible for conductivity. Surprisingly, the ms on the Ir ion almost becomes zero (+0.01μB), turns out to be in a +3 state with t2g3↑t2g3↓eg0 (S = 0) despite +4 along with 1.68/−1.55μB on the Ni+2/Os+5. Finally, MAE value and TC in Os-doped structure increase due to large structural distortions as compared to pristine one which makes the system technologically important.