Insulator-to-half metal transition and enhancement of structural distortions in $$\text {Lu}_2 \text {NiIrO}_6$$ double perovskite oxide via hole-doping

Abstract

Using density functional theory calculations, we found that recently high-pressure synthesized double perovskite oxide $$\text {Lu}_2 \text {NiIrO}_6$$ Lu 2 NiIrO 6 exhibits ferrimagnetic (FiM) Mott-insulating state having an energy band gap of 0.20 eV which confirms the experimental observations (Feng et al. in Inorg Chem 58:397–404, 2019). Strong antiferromagnetic superexchange interactions between high-energy half-filled $$\text {Ni}^{+2}$$ Ni + 2 -$$e_g^2\uparrow$$ e g 2 ↑ and low-energy partially filled $$\text {Ir}^{+4}\,t_{2g}^3\uparrow t_{2g}^2\downarrow$$ Ir + 4 t 2 g 3 ↑ t 2 g 2 ↓ orbitals, results in a FiM spin ordering. Besides, the effect of 3d transition metal (TM = Cr, Mn, and Fe) doping with 50% concentration at Ni sites on its electronic and magnetic properties is explored. It is established that smaller size cation-doping at the B site enhances the structural distortion, which further gives strength to the FiM ordering temperature. Interestingly, our results revealed that all TM-doped structures exhibit an electronic transition from Mott-insulating to a half-metallic state with effective integral spin moments. The admixture of Ir 5d orbitals in the spin-majority channel are mainly responsible for conductivity, while the spin minority channel remains an insulator. Surprisingly, a substantial reduction and enhancement of spin moment are found on non-equivalent Ir and oxygen ions, respectively. This leads the Ir ion in a mixed-valence state of $$+4$$ + 4 and $$+5$$ + 5 in all doped systems having configurations of $$5d^5$$ 5 d 5 ($$t_{2g}^3\uparrow t_{2g}^2\downarrow$$ t 2 g 3 ↑ t 2 g 2 ↓ ) and $$5d^4$$ 5 d 4 ($$t_{2g}^2\uparrow t_{2g}^2\downarrow$$ t 2 g 2 ↑ t 2 g 2 ↓ ), respectively. Hence, the present work proposes that doping engineering with suitable impurity elements could be an effective way to tailor the physical properties of the materials for their technological potential utilization in advanced spin devices.

Large-scale synthesis of mixed valence K3[Fe2S4] with high dielectric and ferrimagnetic characteristics

“… 44 In ceramics, the effects of grain boundaries are commonly interpreted according to the brick layer model. 45 However, in most cases they are more complicated and need to be individually studied and modelled for each case. When 1 is sintered at 723 K, the grain size is comparably small and the ratio of grain boundaries to grains is larger than that of the samples sintered at higher temperatures.…”

Re/Ir@Os-doping induced insulator-to-metal transition in Mott-insulator Ca2FeOsO6: octahedral distortion effects

“…The Re/Ir@Os-doped structures are designed by substituting the Re/Ir atom with one of the Os ions, and results in a 50% dopant concentration as discussed in previous experimental [30][31][32] and theoretical investigations. 33,34 The schematic diagram of the pristine (along the [001]/[010]direction) and Re/Ir@Os-doped (along the [001]-direction) CFOO DPOs are shown in Fig. 1(a)/(b) and (c), respectively.…”

The electronic, magnetic, and optical properties of double perovskite La2BB′O6 (B = Cr, V and B′ = Co, Ni and Sc)

“…These have attracted attention due to their ability to accommodate an extensive range of rare earth elements at the A-site, significantly modifying the bond length and bond angle of the octahedra, and two different types, sizes and valence states of cations at the B′ and B′′-sites, offering the opportunity to manipulate, tune and tailor their physical properties according to industrial and technological needs. 7,8 ODP usually exhibit half-metallic (HM), 9,10 ferrimagnetic (FiM), 11,12 ferromagnetic (FM), 13,14 antiferromagnetic (AF), 15,16 half-metallic ferromagnetic (HM-FM), 17,18 half-metallic ferrimagnetic (HM-FiM), 17,19 nonmagnetic (NM), 18,20 ferroelectric (FE), 12,21 and semiconducting (SC) 12,18,21 responses near room temperature. Half-metallic materials have well-defined band gaps in one spin state and metallic bands in the other spin channel.…”