Electronic structure and estimation of Curie temperature in Ca2BIrO6 (B = Cr, Fe) double perovskites

Abstract

We investigate the electronic and magnetic properties of Ca2CrIrO6 and Ca2FeIrO6 by means of density functional theory. These materials belong to a family of recently synthesized Ca2CrOsO6 whose properties show possible applications in a room temperature regime. Upon replacement of Os by Ir in Ca2CrOsO6, we found the system to exhibit a stable ferrimagnetic configuration with a bandgap of ∼0.25 eV and an effective magnetic moment of ∼2.58μB per unit cell. Furthermore, when chemical doping is considered by replacing Cr with Fe and Os with Ir, the material retains the insulating state but with a reduced bandgap of 0.13 eV and large increment in the effective magnetic moment of ∼6.68μB per unit cell. These observed behaviors are noted to be the consequence of the cooperative effect of spin–orbit coupling; Coulomb correlations from Cr-3d, Fe-3d, and Ir-5d electrons; and the crystal field effect of the materials. These calculations suggest that by chemical tuning, one can manipulate the bandgap and their effective magnetic moment, which may help in material fabrication for device applications. To check further the suitability and applicability of Ca2CrIrO6 and Ca2FeIrO6 at higher temperatures, we estimate the Curie temperature (TC) by calculating the spin–exchange coupling. We found that our findings are in a valid TC trend similar to other perovskites. Our findings are expected to be useful in experimental synthesis and transport measurement for potential applications in modern technological devices.

First Principle Study of the Structural, Electronic, Magnetic and Magneto-optical Properties of Double Perovskites Ca 2 TMIrO 6 (TM=Fe, Co) Compounds

“…The results of the relaxation for lattice constants and volume for both compounds are summarized in Table 1, where we see that the ferrimagnetic (FIM) ground state is the most stable since the corresponding energy is minimal. The results also revealed that the two compounds exhibit a monoclinic structure (space group P21/c) figure 1; our theoretical results agree with those reported in reference [16,20].…”

“…To explore the effect of spin-orbit coupling and on-site Coulomb repulsion (DFT+SO) and (DFT+SO+U) were introduced. The added Hubbard potential U was used with U=1.5 eV for Ir and U=4 eV for Co [20] and U=5 eV for Fe [16]. The convergence criterion for the self-consistent calculation was 0.0001 Ry for the total energies.…”

“…Using experiments of magnetic susceptibility and x-ray powder diffraction, they found that The Ca 2 FeIrO 6 compounds form in a monoclinic structure, space group P21/n, with the antiferromagnetic ground state. The theoretical study using density functional theory was done by Bhandari et al [16], which predicts that the material should have a band gap of 0.13 eV and a significant effective magnetic moment of 6.68 µ B per unit cell. Our work aims to study the structural, electronic and magneto-optical properties for the monoclinic structure of double perovskites Ca 2 TMIrO 6 (TM=Fe, Co).…”

Electronic and Magnetic Properties of K2Mn3S4

“…GaAs, as an example, has the following benefit over Si: (i) A six times increase in electron mobility that enables quicker functioning; (ii) A wider band gap, which enables power devices to operate more faster at higher temperatures and produces less thermal noise at ambient temperatures; (iii) Its optoelectronic properties are more advantageous than those of indirect band gap Si because it has a direct band gap; (iv) For alloying, ternary and quaternary compositions are recommended. In compound semiconductors, nonmagnetic (NM), ferromagnetic (FM), antiferromag-netic (AFM) and ferrimagnetic (FIM) semiconductor are extensively studied theoretically as well as experimentally [3][4][5][6]. As a NM semiconductor transistor, bulk inversion asymmetry in (110) InAs/GaSb/AlSb heterostructures was proposed [7].…”

Electronic Structure and Magnetic Properties of Double Perovskites Ca2MnIrO6

“…Likewise, layered perovskites Sr4Co3O10 and Sr4Rh3O10 shows HM-FM state [22] while FiM to HM-FiM and HM-AFM were observed in Pr2-xSrxMgIrO6 (x = 0 to 2) [23]. Many DPs are reported to have high Curie temperature (TC) [24][25][26]. One such example is Sr2CrOsO6 whose Tc is found to be 725 K [27].…”