investigate the magnetic excitations in the weakly distorted face-centered-cubic (fcc) iridate double perovskites La2ZnIrO6 and La2MgIrO6. The combination of spin-orbit coupling, inter-orbital hybridization and symmetry-allowed trigonal distortion leads to a rich phase diagram with tunable ferromagnetic order, topological C1 and 2 Chern bands, and a C 2 quantum anomalous Hall insulator regime. Abstract (summary We first present theoretical analysis of powder inelastic neutron scattering experiments in Ba2FeReO6 performed by our experimental collaborators. To interpret the experimental data, we develop a local moment model, which incorporates the interaction of Fe spins with spin-orbital locked magnetic moments on Re, and show that it captures the experimental observations. Our findings highlight how write my essay joke site even seemingly conventional magnetic orders in oxide materials containing heavy transition metal ions may be driven by highly-directional exchange interactions rooted in strong spin-orbit coupling. Incorporating both strong spin-orbit coupling and the Hubbard repulsion on Re leads to a band structure consistent with ab initio calculations. Motivated by experiments on the double perovskites La2ZnIrO6 and La2MgIrO6, we lastly study the magnetism of spin-orbit coupled j_eff 1/2 iridium moments on the three-dimensional, geometrically frustrated, facecentered cubic lattice. The symmetry-allowed nearest-neighbor interaction includes Heisenberg, Kitaev, and symmetric off-diagonal exchange. A Luttinger-Tisza analysis shows a rich variety of orders, including collinear AII type antiferromagnetism, stripe order with moments along the 111-direction, and incommensurate non-coplanar spirals, and we use Monte Carlo simulations to determine their magnetic ordering temperatures.
First Principles Study of Double Perovskites and
Double perovskites thesis
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We then develop a corporate responsibility introduction for essays tight-binding model of the double perovskite Ba2FeReO6, a room temperature ferrimagnet with correlated and spin-orbit coupled Re t2g electrons moving in the background of Fe moments stabilized by Hundâ s coupling. Ba2FeReO6, a member of the double perovskite family of materials, exhibits half-metallic behavior and high Curie temperatures Tc, making it of interest for spintronics applications. We show that for such 3d/5d double perovskites, strong correlations on the 5d-element (Re) are essential in driving a half-metallic ground state. The uncovered interplay of strong correlations and spin-orbit coupling lends partial support to our previous work, which used a local moment description to capture the spin wave dispersion found in neutron scattering measurements. Models with dominant Kitaev exchange seem to most naturally account for the neutron data as well as the measured frustration parameters of these materials, while the uniaxial Ising anisotropy does not. For the purpose of this thesis, it is essential to clearly delineate sections. Electronic and magnetic properties of double perovskites and oxide interfaces. Concept of this thesis with application to the half-metallic ferromagnetism. Multiferroic Compounds with Double- Perovskite Structures. Yuichi Shimakawa, Masaki Azuma and.
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